review article bioactive phytochemicals: bioactivity, sources,...

Review ArticleBioactive Phytochemicals Bioactivity Sources Preparationsandor Modifications via Silver Tetrafluoroborate Mediation

Matthew C Achilonu and Dennis O Umesiobi

Department of Agriculture Central University of Technology Free State 1 Park Road Bloemfontein 9300 South Africa

Correspondence should be addressed to Matthew C Achilonu machilonucutacza

Received 12 August 2014 Accepted 5 March 2015

Academic Editor Patricia Valentao

Copyright copy 2015 M C Achilonu and D O Umesiobi This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

This review provides an overview of the biological activities natural occurrences and the silver tetrafluoroborate- (AgBF4-)mediated synthesis of proanthocyanidins glycosides N-heterocyclic alkaloid analogues (of pyrrole morphine quinolineisoquinoline and indole) furan analogues and halocompounds AgBF

4has been reviewed as an effective reaction promoter used

extensively in the synthesis of relevant biologically active compounds via carbon-carbon and carbon-heteroatom bonds formationThe literatures from 1979 to April 2014 were reviewed

1 Introduction

Naturally occurring bioactive compounds are ubiquitous inmost dietary higher plants available to humans and livestockThe natural products such as plant extracts provide unlimitedopportunities for new drug discoveries mostly because ofplethora of varieties of chemicals [1 2] Literally relativeto available synthetic medicines thousands of accessiblemedicinal and agricultural phytochemicals are safer andlargely more effective alternatives with less adverse effectsFor this reason coupled with advancing microbial resistanceto the synthetic drugs ethnopharmacognosy is rapidly gain-ing world recognition [2] The strong growing value andinterest in the crucial role that nutrition plays in maintaininghuman health animal health productivity and reproductiveperformance of livestock and poultry are greatly recognised[3] Sasidharan et al (2011) and other authors have sturdilyexpressed useful biological activities of phytochemicalsTheyobserved that plant chemicals exhibit anticancer antimicro-bial antioxidant antidiarrheal analgesic and wound healingactions on animals [2]

The most popular phytochemicals are the polyphenolicswhich consist of flavonoids and phenolic acids that formthe building blocks for polymeric tannins (hydrolysable andcondensed tannins or proanthocyanidins) [4] Flavonoidsare large collection of plant secondary metabolites whose

chemical structures are based on a C6-C3-C6carbon ring

system 1 and consist of five major subgroups flavones 2flavonols 3 flavanones 4 flavanols 5 and anthocyanidins6 (Figure 1) Being universally distributed in green plantkingdom flavonoids therefore form an integral part ofhuman and animal diets It is well known that flavonoidsdisplay a potpourri of biological activities in plants thatbiosynthesize them and in humans and livestock that feedon those plants and allied products The bulk of animal feedwhich is of plant origin is known to contain a range ofdifferent biologically active compounds such as flavonoidstocopherols tocotrienols and carotenoids [3] Reports showthat in a particular animal feed portion the bioactivityof flavonoids is about twice more than other bioactivesource compounds [3] Flavonoids play such important roles[5] in situ as signal 37 molecules [6] phytoalexins [7 8]detoxifying agents [9ndash11] and stimulants for germination ofspores [12ndash15] Additionally they also act as UV-filters [1617] in temperature acclimation [18] drought resistance [19]pollinator attractants [20] and allelochemical agents [21 22]For the scope of this review paper our focus was limited toproanthocyanidins polymers of flavanols (catechin) and theanalogues (Figure 1) [23]

Glycoside compounds are another important group ofbioactive phytochemicals They essentially constitute hor-mones sweeteners alkaloids flavonoids antibiotics and so

Hindawi Publishing CorporationJournal of ChemistryVolume 2015 Article ID 629085 22 pageshttpdxdoiorg1011552015629085

2 Journal of Chemistry

OHO

OH

A C B OHO

OH O

OHO

HOHO HO

OH OOH

OH

OH OHOH

OH

OHOH

OH

OH

O

O

O O

1

2

3

456

78

Flavanone 4 Flavanol 5 Anthocyanidin 6

Base structure 1 Flavone 2 Flavonol 3

6998400 5998400

4998400

39984002998400

+

Figure 1 Base structure and subgroups of flavonoids

OO

OH

OH

OH

O O OHOH

HO

O

O OHOHOH

OHO

HO

OHO

O

O

O

OHO

OH

OMe

OHOH

O

O O

OHHO

HOOH

HO

HOHO

OHO

OH

OH

OMe

O

Glc Glc

CAF

CAF

Glc

Glc

CAF

Glc

7

8

Heavy blue anthocyanidin(peonidin acyl-glycoside)

Quercetin 3-O-rhamnopyranosyl(1rarr2)-

+

= 120573-maltoside 10R1 = H = Silybin 9

CH2OR1

R1

glucopyranoside-7-Orhamnopyranoside

Figure 2 Natural polyphenolic flavonoid glycosides

forth [24] Literature revealed that amongst these glycosidesare a range of natural polyphenolic flavonoid glycosidesrichly found in legume plants (Figure 2) [25ndash28]

Typical alkaloidsmainly derived fromplant sources are alarge group of secondarymetabolites containing usually basicnitrogen in a heterocycle which are broadly varied in chem-ical structure and in pharmacological action (Figure 3) [29]The toxicity of some alkaloids is widely recognized however

they are a source of many biologically active phytochemicalswith great potential formedicinal and agricultural usesManyalkaloids have attractive pharmacological effects and are usedas medications such as recreational drugs or in entheogenicrituals [30 31]

Furans particularly 23-dihydrofurans are one of theabundant structural motifs found in plants that possessimpressive biological activities and as a result are extensively

Journal of Chemistry 3

NH

NN N

H

Indole 14Isoquinoline 13Quinoline 12Pyrrole 11

Figure 3 Typical basic structure of alkaloids

used in the pharmaceutical flavour insecticidal and fishantifeedant industries [32ndash37]

Another group of phytochemical derivatives that areincreasingly gaining attention in recent times in the agro-chemical and pharmaceutical industries is the halocom-pounds Though they are usually isolated from nature in lowyields the halogenated phytochemicals are known for theirhigh bioactivity [38 39]

Owing to the significance of these rare and sparselyavailable natural compounds to human health and biotascientists have made desperate efforts to mimic nature andmake these compounds more accessible through chemicalsynthetic methods In that pursuit silver tetrafluoroborateproved to be an efficient tool to achieve this purpose AgBF

4

was found to promote a variety of reactions through its abilityto complex with and activate electron rich atoms and bondsunder mild conditions

Our literature search for AgBF4-promoted reactions thus

revealed two reviewed papers published in 2008 coveringsilver-mediated reactions including the AgBF

4-mediated

reactions [40ndash43] Abbiati and Rossi in their review [44]referred to the use of AgBF

4by Liu (2011) to facilitate

their 3-component cascade synthesis of bioactive Pyrrole-2-carboxaldehyde [44 45] These reports were concurrentlysummarized and therefore are excluded from the presentreview A study of the available reports revealed that mostof the compounds synthesized via AgBF

4mediation are

biologically active phytochemicals With this revelation inmind we summarized the publications with the aim ofpursuing two objectives firstly to provide a brief overview ofthe bioactivity and natural occurrences of the main groups ofthe compounds within the scope of this paper and secondlyto review the AgBF

4-promoted synthesis of the compounds

andor analogues Herein we reviewed bioactivity and nat-ural sources of some phytochemicals and formation of suchcompounds andor analogues via AgBF

4-mediated reac-

tions based on published information on AgBF4-promoted

carbon-carbon and carbon-heteroatombond formation since1979 when Fry and Migron record of its use in this regardappeared until April 2014

2 Proanthocyanidins

Proanthocyanidins oligomers andor polymers of flavan-3-ols are among the most abundant naturally occurringpolyphenolic plant metabolitesThey are commonly availablein different parts of plants (eg legumes cocoa) and cropssuch as fruits (grapes apples and pears) nuts seeds flowers

and bark [46] Proanthocyanidins display awide range of bio-logical activities such as antioxidant antibacterial antiviralantimutagenic anti-inflammatory hypertensive and otherheart related diseases [47 48] Their high significance in thegeneral well-being of animals warranted intensive studies byresearchers on their sources and accessibility Hence Steyn-berg and co-workers [49] (1998) and other research groups[50 51] have widely exploited different ways of synthesizingthe largely varied proanthocyanidin compounds

A popular methodology in this regard involved using asubstrate bearing a leaving group that contains oxygen orsulphur heteroatom The affinity of AgBF

4towards oxygen

and sulfur is exploited to enhance capabilities of the leavinggroup [49ndash51] This property has been explored to creategood routes to obtain procyanidins 17 under neutral reactionconditions The protocol involves treating a mixture of 4120573-benzylsulfanylepicatechin 15 and catechin 16 in THF withAgBF

4(25 equiv) for 1 h at 0∘C to obtain procyanidin B-1

in 38 yield (Scheme 1) [49]A 2-mercaptobenzothiazole is used to obviate the offen-

sive odour associated with 4-thioderivatives Then conden-sation of 18 and 19 in dry THF in the presence of anhydrousAgBF

4at 0∘C yielded the procyanidin oligomers (20 21 and

22) as presented in Scheme 2 [50]The ability of AgBF

4to activate OH groups to syn-

thesize ether-linked proanthocyanidins (proteracacinidinand promelacacinidin) was further explored The protocolinvolved treating a mixture of the epioritin-4120573 23 and 4120572-ols 24 in dry THF at 0∘C with AgBF

4for 90min under

nitrogen before the reaction was quenched with water Afterworkup and purification processes including acetylation theexpected products epioritin-(4120573 rarr 4)-epioritin-4120572-ol 25(91) and epioritin-(4120573 rarr 3)-epioritin-4120572-ol 26 (78)were obtained as the octa-O-acetyl derivatives accompaniedby a C-C-linked compound epioritin-(4120573 rarr 6)-epioritin-4120572-ol 27 (Scheme 3) [51]

The AgBF4activating C-H group between carbonyl and

aryl functional groups affords a novel synthesis of proan-thocyanidins from 3-oxo-flavans accessible from readilyavailable flavan-3-ols viaDess-Martin periodinane oxidationthus circumventing the need for C-4 functionalization Incontrast with flavan-3-ol based syntheses where the C-3stereochemistry determines the C-4 stereochemistry the 3-oxo-flavans have no stereochemistry on C-3 and the C-2 determines absolute configuration on C-4 giving accessin hitherto synthetically unavailable 34-cis procyanidins(Scheme 4) [52]


O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

15

16

17

Procyanidin B-1

+

SCH2Ph

AgBF4 in THF

0∘C 1h

Scheme 1 Interflavanyl bond formation in procyanidins under neutral conditions

S N

O

OHS

BnO

OBn

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

O

OBn

OBn

OBn

BnO

OH

O

O

BnO OBn

OBn

O

HO

OBn

BnO

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

OBn

OBn

OBn

O

OH

BnO

OBnO

OBn

OBn

OBn

BnO

OHO

OH

BnO

OBn

OBn

OBn

18

21

19

20

22

AgBF4

THF 0∘C

+

Scheme 2 Synthesis of procyanidin oligomers using 4-[(2-benzothiazolyl)thio] derivative

The requirement of an excess of AgBF4and the observa-

tion of a silver mirror (reduction of Ag1 to Ag0) may indicatean oxidative mechanism (Scheme 5) [53]

The BF4

minus counter ion probably assists in stabilizingthe 4-carbocation 34 via the quinone methide tautomer36 Another major advantage of this synthesis is that noself-condensation was observed as was the case with theconventional syntheses based on a flavan-3-ol with a C-4leaving group

3 Glycosides

Natural occurring bioactive glycosides are many and aremainly essential class of compounds such as hormonessweeteners alkaloids flavonoids and antibiotics [24] It iswidely attested that the glycosidic moiety can be crucialfor the compoundrsquos activity or in certain cases it onlyimproves its pharmacokinetic properties such as circula-tion elimination and concentration in the body fluid [24]


O

O

O

O

O

O

O

O

O

O

+

26

27

23

OAcOAcOAc

OAc

OAc

OAc

OAcOAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

AcOAcO

AcO

AcO

AcO

AcO

AcO

AcO

AcOHO

HO

OH

OH

OH

OH

OHOH

OH

OH24

(1) AgBF4THF

(2) PyAc2O

25

Scheme 3 Synthesis of ether-linked proteracacinidins 25 and 26 and the C-C coupled analogue 27

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

O

OMeO

MeO

MeO

MeO O

O

O

O

28

+

2930

31

OH

OH

AgBF4 THF

Reflux 4h

30 (38) 31 (6)

Scheme 4 Condensation reaction between 28 and 29

Glycosides are more water soluble than aglycons thereforeattaching glycosidic residue into the molecule will increasethe compoundrsquos hydrophilicity Consequently the effect willbe seen in the compoundrsquos pharmacokinetic activities suchas inhibiting cell uptake of the glycoside by building placentabarrier thus preventing foetal intoxication by metabolites ofxenobiotics [24] Varieties of natural polyphenolic flavonoidglycosides (Figure 2) are found in abundance in legumeplants [28] Glycoflavonoids mainly isoflavonoids (egquercetin 3-O-rhamnopyranosyl(1 rarr 2)-glucopyranoside-7-O-rhamnopyranoside 7) present in legumes such as Vicia

faba and Lotus edulis (Leguminosae) are purported toexert chemopreventive actions [25] on certain cancer types(colon breast and prostate) [26] and cardiovascular diseases[27] Flavonoid glycosides are prepared synthetically usuallyfor pharmaceutical purposes [24] Anthocyanin glycosidesimprove the antioxidant and ldquodeepeningrdquo colour stabilizationcontrolled by the glycosyl residue A typical molecule isthe ldquoheavy blue anthocyanidinrdquo peonidin acyl-glycoside 8Another example is Silybin 9 a flavonolignan extracted fromseeds of milk thistle (Silybum marianum) used as potenthepatoprotectant and an antidote in mushroom poisoning


O

O

O

O

O

O

H

O

O

O

O

BO

O

D

CA

O

O

O

O28 32

33

34

35

3637

3839

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe OMe

OMe

OMe

OMe

OMe

OMe

OMe

MeO MeOMeO

MeO

MeOMeO

MeO

MeO

MeO

MeO

MeO

minusBF4

minusBF4

Ag+minuse 1

Ag+minuse 1

+

+

+

+

minusH+

minusH+

∙+

∙

∙∙

Scheme 5 Proposed mechanism for oxidative synthesis of 30 and 31 based on the model reaction

However the major drawback of water solubility of thisphytochemical compound was dealt with by chemical glyco-sylation to afford compound 10 [24 28]The demand for bio-logically relevant and therapeutically active oligosaccharidesis on the increase in recent times This has spurred syntheticbiologists and chemists to increase efforts in developingeffective glycosylation methods for oligosaccharides

A typical work is that of Kaeothip et al (2008) whoused silver tetrafluoroborate to activate glycosyl donors suchas glycosyl halides trichloroacetimidates and thioimidates[53 54] Glycosyl thioimidates 40 and 41 could be selec-tively activated in the presence of thioglycosides to afforda simple one-pot synthesis of trisaccharides (Scheme 6)The glycosyl acceptor (S-ethyl glycoside) is expected towithstand AgBF

4activation but later readily activated when

N-iodosuccinimide (NIS) was added followed by addition ofnew acceptor methoxy glycoside 43

4 Alkaloids

Alkaloids typically derived from plant sources are a largegroup of secondary metabolites containing usually basicnitrogen in a heterocycle The types and occurrences ofalkaloids [29] within the scope of this paper are as follows(Figure 3) pyrrole Coca spp (Erythroxylaceae) quinoloneCinchona spp (Rubiaceae) Remijia spp (Rubiaceae)Angostura or cusparia bark Galipea officinalis (Rutaceae)isoquinoline Papaver somniferum (Papaveraceae) Corydalisand Dicentra spp (Fumariaceae) numerous genera of theBerberidaceae Ranunculaceae and Papaveraceae Cephaelisspp (Rubiaceae) Curare obtained from plants of Menisper-maceae Papaver somniferum (Papaveraceae) Erythrina spp(Leguminosae) Leucojum aestivum (Amaryllidaceae) andindole (benzopyrrole) Claviceps spp (Hypocreaceae) Riveacorymbosa Ipomoea violacea (Convolvulaceae) Physostigma


O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe

Scheme 6 AgBF4as a potent promoter for chemical glycosylation

venenosum (Leguminosae) Rauwolfia spp (Apocynaceae)Aspidosperma spp (Apocynaceae) Catharanthus roseus(Apocynaceae) and Strychnos spp (Loganiaceae) Thoughmany alkaloids are toxic some have pharmacologicaleffects and are used as medications recreational drugs orin religious rites [30 31] Only N-heterocyclic alkaloidssynthesized via AgBF

4mediation are summarized here

41 Pyrroles Pyrroles are a very important class of hete-rocyclic compounds serving as key structural characteristicof many bioactive natural products and pharmaceuticalresources [55]Many classical reactionmethods requiring theuse of prefunctionalized substrates to obtain bioactive pyrroleanalogues have been developed [56]

In 2010 Buscemi et al reported the use of ligand-AgBF4

complex to synthesis substituted pyrrole not involving pre-functionalized substrate This reaction allows hydroary-lations of ethyl 3-phenylpropanoate 46 with 1-methylpyrrole45 to obtain the ethyl 3-(1-methyl-1H-pyrrol-2-yl)-3-pheny-

lacrylate 48 in 70 yield The C-H bond functionalization ofan aromatic heterocycles requires the chelating dicarbene Pd(II) ligand 47 to be activated by extraction of the halides withsilver additives (AgBF

4) possessing a noncoordinating anion

(Scheme 7) [56]Reports on an efficient one-pot AgBF

4-catalyzed and

phenyliodine diacetate- (PIDA-) mediated synthesis of poly-substituted pyrroles in which dimethyl but-2-ynedioate wastreated with various amines (via tandem reactions) affordedcorresponding pyrroles in moderate to excellent isolatedyields of 53ndash88 [55] By the protocol a facile and highlyefficient C-N and C-C bond formation method to constructa direct pyrrole framework (Scheme 8) as described by theproposed reaction mechanism (Scheme 9) was established

42 Morphine Morphine the major alkaloid in opium adried sap of the unripe seed capsule of poppy (Papaversomniferum) is an analgesic However it has serious sideeffects such as being additive and causing nausea decrease in


N Ph N

Ph

HMe

L =

4546

48

47

+

Palladium (II) chelatingcarbene complex

Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br

Scheme 7 Pd carbene complex AgBF4-mediated synthesis of compound 48

R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3

Dioxane 100∘C 3hR2O2C

H2N

CO2R4

Scheme 8 Synthesis of polysubstituted pyrroles from various alkynoates and amines

blood pressure and depressed breathing [57] Morphine wasfirst isolated in 1805 and its first synthesis in the laboratorywas in 1952

After three decades a concise methodology to morphi-nan ring system 64 was described [58] The reaction mecha-nism relies upon intramolecular trapping of an aziridiniumcation generated in situ by the treatment of pyrrolidine 63with AgBF

4 The protocol involves treatment of a solution

of 63 (54mg 013mmol) in 3mL of toluene with AgBF4

(56mg 029mmol) in 2mL of toluene and an immediateformation of AgCl precipitate was purported to drive thereaction forward affording the desired compound 64 (19mg56) following purification on silica gel preparative TLC(eluting with 12 MeOHCH

2Cl2) (Scheme 10)

43 Quinolines Quinolines are made up of compounds thatexhibit extensive bioactivities According to the record ofSouth and Liebeskind 1984 benzoquinones (methylbenzo-quinone ethylbenzoquinone) are defensive agents againstpredators in arthropods [59] while menaquinones playimportant role in blood clotting process [60] and manyderivatives of natural products such as benzoquinone naph-thoquinone and anthraquinone show significant antibiotic

andor antitumor properties [61] It is widely recordedthat polysubstituted dihydroquinolines are important build-ing blocks in natural products exhibiting a broad rangeof bioactivities (psychotropy antiallergy anti-inflammatoryand estrogen) and potential pharmaceutical applications [62ndash67]

The first example of a silver-catalyzed regioselective dom-ino reaction between anilines and alkynes was reported toobtain partially hydrogenated quinoline moiety bearing dif-ferent functional groups (polysubstituted 12-dihydroquin-olines) [68] The work involved treating Phenylethyne 65(10mmol) and phenylamine 66 (40mmol) with AgBF

4

(97mg 005mmol) HBF4

(112mg 007mmol) andBF3sdotEt2O (113mg 008mmol) as cocatalysts for 12 h at 160ndash

190∘C to yield 67 (77) (Scheme 11) A proposed mechanismis given in Scheme 12

Theworks of Tang et al (2010) demonstrated further abil-ity of AgBF

4in heteroatoms activation as well as alkyne group

reactions In the presence of AgBF4 2-alkynylbenzenamines

and tetraalkylthiuram disulfides reacted via ammonolysis-cyclization tandem to produce quinoline thiaz-analogue4-methylene-4H-benzo[d][13]thiazin-2-amines (Scheme 13)[69]


Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙

Scheme 9 A plausible mechanism for the additionoxidative cyclization reaction in the formation of 52

ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene

Scheme 10 AgBF4-mediated synthesis of morphinan

NH

H

HH

65 66

67

Cat AgBF4Cat HBF4190∘C

CH3NH2+

Scheme 11 A silver-catalyzed efficient synthesis of 12-dihydroquinoline derivatives


NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2

Scheme 12 Proposed mechanism for the synthesis of 67

N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C

Scheme 13 Synthesis of 4-methylene-4H-benzo[d][13]thiazin-2-amines

44 Isoquinoline Crinine alkaloids are our focus here Theyrepresent an important subclass (Galantamine) within thelarge family of Leucojum aestivum (Amaryllidaceae) alka-loids Members of this subclass exhibit attractive biologi-cal properties including immune-stimulatory cytotoxic andantimalaria activities [70] Accordingly these natural prod-ucts (eg maritinamine erythramine etc) interests andsynthetic studies have proved this since 1966 when it was firstsynthesised [70ndash83] Cyclopropanes are ubiquitously basicstructural moiety in a variety of the naturally occurring alka-loid compounds [84] Banwell (2008) has demonstrated theuse of AgBF

4to open the strained cyclopropanes and trapped

the resulting allylic cation by the carbamate nitrogen [70 85]to synthesize maritinamine via an arylated hexahydroindolefrom 66-dichlorobicyclo[310]hexane (Scheme 14)

It was purported that deprotonation of gem-dihalopro-pane 79 with LiHMDS and subsequent reaction of the con-jugate base with AgBF

4affords a diastereoisomeric mixture

of products 80 (26) and its C-3 epimer 81 (30) [85] andthe completion of the synthesis of erythramine 82 took threefurther steps as shown in Scheme 15

45 Indole Indole ring system is a prevalent structuralmotif extensively present in naturally occurring compoundsand its derivatives display a broad variety of powerful

and therapeutically fascinating biological activities [86] Forexample serotonin alkaloid is a bioactive alkaloid knownas a neurotransmitter in the cardiovascular system bloodcells and the peripheral and central nervous system Psilocinand psilocybin are the main alkaloids in hallucinogenicmushrooms belonging to the genus Psilocybe [87] In 1977the first isolation of hallucinogenic bisindolylalkane wasobtained and subsequently several bioactive bisindolylalka-nes have been isolated from nature and this pulled a lotof scientific attention Typically some indole derivatives (3substituted indoles) are known to exhibit various biologicalactivities including antibacterial cytotoxic antioxidative andinsecticidal activities [88] Following this line of thoughtsynthetic chemists in their pursuit for more efficient routes tosynthesize the richly endowed indole molecules shifted fromthe common methods of preparing indole scaffold (FischerBischler Reissert Madelung and Smith methodologies) toorganometallic reagents of which coinage metals (silver andgold) were the first choice [86]

Reports by Ko et al (2013) established that stable bis-cyclometalated gold(III) catalysts 85 can exhibit high cat-alytic activity in organic synthesis via goldndashsilver dual catal-ysis for substrate activation [89] They also supposed thatsilver salts can react synergistically with bis-cyclometalatedgold(III) complexes in the indole alkylation Thus using


NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75

78(minus)-epi-Maritinamine

77(minus)-Maritinamine

Et3N

minus(Boc) 2O

minusHCl

∙∙

Scheme 14 Synthesis of epi-Maritinamine 78

85 (25mol) with AgBF4

(50mol) alkynyl alcohol83 reacted with N-methylindole 84 to obtain the natu-rally occurring alkylated indole analogue (3-(tetrahydro-2-methylfuran-2-yl)-1-methyl-1H-indole) 86 in 80 isolatedyield at room temperature in 2 h (Scheme 16) Poor yields (10ndash13) or no product formation was found when only a singlemetal catalyst was used

Shaikh andChen (2011) showed that carbonyl compounds88 can be activated towards nucleophilic attack by indoles 87with AgBF

4to synthesise bisindolylmethanes 89 in excellent

yields [88]Thus reaction of p-nitrobenzaldehyde and indolein the presence of AgBF

4(10) in methylene chloride gave a

96 yield at room temperature within 2 h (Scheme 17) Theproposed mechanism is presented in Scheme 18

In the work of Grierson et al (1992) it was discoveredthat condensation of allylic aminonitrile 93 and diacid 96 ledto the production of 4-[bis(methoxycarbonyl)methyl]-3-(3-indolylmethyl)-1-methyl-1456-tetrahydropyridine 97 [90]The C-7 indole-substituted aminonitriles 93 or 95ab whentreated with AgBF

4 yielded the desired reactive intermediate

(56-dihydropyridinium salt 94) which on reaction withsodium dimethyl malonate 96was converted to the 97 (76)(Scheme 19)

Another example is AgBF4-mediated cyclopropane ring

opening and trapping of the intermediate cation in thesynthesis of a diastereoisomericmixture ofHapalindoleC 100(Scheme 20) [85]

Kuehne et al (1991) recorded successful enantioselectivesynthesis of vinblastine [66] a natural occurring bioactive

binary indole-indoline alkaloidThe compound generally hasa long history of investigation and thus has been extensivelyreviewed since it was first synthesized in 1967 [91ndash94]Here we therefore summarize accessing the compound viathe synthesis of the intermediate promoted by AgBF

4 The

authors established that the reaction of the chloro-imine101 with silver tetrafluoroborate and a natural compoundvindoline hydrofluoroborate provided the tetracyclic C161015840-C141015840 parf indolenine 102 as white foam (Scheme 21) [95]

5 Furans

Furan structuralmotif occurs in a variety of natural productsand the 23- and 34-substitutions are the most abundantin nature [96 97] Typically 23-dihydrofurans are amongstthe structural units ubiquitously found in natural productsand they exhibit impressive biological activities Accord-ingly they are extensively used in the pharmaceuticals asflavourant insecticidal and fish antifeedant industries [32]Thus researchers are prompted to search for better methodsto synthesize or modify the natural products

Hence Xia et al (2011) reported their investigation in theuse of AgBF

4to generate carbenes from diazo compounds

[32] namely (1) several Ag(I) containing catalysts were usedfor the synthesis of 23-dihydrofurans starting from 2-diazo-55-dimethyl cyclohexanedione 103 and styrene 104 (2)Ag2O Ag

2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C

for 10 h gave no cycloadducts while with AgBF4(10mol)

in toluene at room temperature for 48 h the expected


O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79

(i) LiHMDS THFminus40 to 0∘C

(ii) AgBF4 0 to 18∘Cthen 45∘C 3h

Cl Cl

80MeO

81

MeO82

MeO

Scheme 15 Synthesis of (-)-erythramine 82

N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)

Bis-cyclometalated gold(III) complex

BF minus4

77

86

AgBF4 (5mol)

Scheme 16 Gold(III) complex silver-catalyzed cyclization-addition reactions of alkynyl alcohols 83 and substituted indoles 84

product 105 was produced in 22 yield (Scheme 22) and (3)raising the temperature to 70∘C increased the yield to 47but by using the ionic liquid 1-butyl-3-methylimidazoliumtetrafluoroborate ([Bmim]BF

4) as a cocatalyst the yield was

increased to 71 The general procedure for the synthesisinvolves addition of silver tetrafluoroborate (010mmol) and(Bmim) BF

4(01mL) to a solution of cyclic diazodicarbonyl

compound 103 (10mmol) and the corresponding olefin 104(50mmol) in toluene (20mL) at room temperature Thereaction mixture was stirred at room temperature for 24 h orat 70∘C for 5 h and the mechanism is given in Scheme 23

AgBF4

has also been used to activate trimethylsi-lyl enols as nucleophiles in substitution reactions In

a study [96] 23-diiodo-1-(phenylsulfonyl)-1-propene (DIP)109 and (cyclohex-1-enyloxy)trimethylsilane (CH-TMS) 110were treated at 25∘C in methylene chloride (005M) with20 equivalents of AgBF

4to obtain iodo-(phenylsulfonyl)

ketone 111 Addition of triethylamine in THF at 25∘C cyclizedthe ketone compound to form the 2-phenylsulfonylmethylsubstituted furan 112 (Scheme 24)

6 Organohalogen Compounds

According to Gribble (2012) the number of naturally occur-ring organohalogen compounds (particularly halogenatedalkaloids) has grown from a dozen in 1954 to gt5000 at


O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2

Scheme 17 Synthesis of 3-substituted indole derivatives

O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1

Scheme 18 AgBF4-mediated synthesis of C-7 indole-substituted aminonitriles

N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC


the time [98] However not many compounds containingfluorine atom(s) have been found in nature [39ndash100] Never-theless it is widely recognised that these compounds exhibitinteresting biological activities [101ndash106] A typical example iskinamycin D [101] produced by Streptomyces murayamaensis

(5-diazobenzo[b]fluorine) which is a naturally occurringdiazo compound that possesses modest antitumor proper-ties and antibiotic activity against Gram-positive organisms[101ndash105] Again record shows that introducing fluorineinto organic molecules more often than not significantly


O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF

Scheme 20 Synthesis of Hapalindole C

N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3

Scheme 21 Synthesis of indolenine 102

O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2

Scheme 22 Synthesis of 23-dihydrofurans 105

improves their physical chemical and biological properties[106] These reactions have been demonstrated in somecompounds such as steroids Steroids are important naturallyoccurring bioactive compounds Unfortunately most of thesecompounds lackmethods for their synthesis and fluorinationhas been a gateway to access these rare compounds [107]The report of Wang et al (2013) and other authors expressedthat arene compounds with fluorine or a trifluoromethylsubstituent display unique pharmaceutical properties suchas improved metabolic stability and lipophilicity For thisreason a large number of drug candidates containing ArFand ArCF

3are routinely evaluated in modern drug discovery

[108ndash111] Given that fluorinated compounds are notablysparsely available from nature their chemical synthesis arehighly challenging [112 113] Accordingly fluorination ofmolecules has gained a prestigious position in the design andsynthesis of biologically active compounds [39]

Studies by Wang et al (2013) [108] revealed that AgBF4

in a nonpolar solvent (such as toluene) was most effective inpromoting the substrate cyclization and subsequent fluorina-tion to afford 96 product yield The general procedure forthe stoichiometric fluorination reaction involves dissolving113 (01mmol) and AgBF

4(015mmol) in 50mL of toluene

under inert atmosphere and the resultingmixturewas stirredat 90∘C for 2 h Thereafter the crude reaction mixture wasfiltered through a small column packed with silica gel and therequired product 114was isolated by column chromatographyon silica gel (Scheme 25) A proposed reaction mechanism isshown in Scheme 26

It was recently illustrated [107] that P2Pt-dicationic

catalysts can mediate enantioselective cation-olefin 120cyclizationfluorination reactions of the polyenes to yieldC3-fluorinated carbocycles Their catalyst formulation iscomprised of 10mol (S)-(xylyl-phanephos)PtI

2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙

Scheme 23 Proposed reaction mechanism to afford the 23-dihydrofuran

HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I

Scheme 24 Synthesis of substituted furans 112

TsNR

TsN

R

F

(15 equiv)

tolueneR = 1-hexynyl

113114

nBu

nBu

AgBF4

∘90 C 2h

Scheme 25 Synthesis of compound 114

AgBF4 30mol NCC

6F5 and stoichiometric quantities

of XeF2and TMSOMe which at 0∘C provided moderate

to quantitative yields of 121 (49ndash80) with enantiomericexcess (10ndash81) and low to trace yields of 122 (22-trace)(Scheme 27)

The fluoride in the BF4

minus can be liberated as an Fminusnucleophile Following this line of thought 120572-fluorocarbonylmolecules 124 can be prepared via the substitution of car-bonyl 120572-bromo substituents (Scheme 28) presumably vianeighbouring group participation by the carbonyl oxygen(Scheme 29) to obtain 120572-fluorocarbonyl compounds [114]

Another example of BF4

minus participation in fluorinationreaction via halogen-exchange is in the synthesis of triflu-oromethyl sulfides [115] gem-difluorides and trifluorides[116] For the sulfides the general procedure involved treat-ment of aprotic solution of mercaptan 126 with a base

TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus

Scheme 26 A proposed reaction mechanism for compound 108

(NaH) and thereafter with CF2Br2or CF

2BrCl The resulting

bromodifluoromethyl sulfide 127 was subsequently treatedwith AgBF

4to obtain desired trifluoromethyl sulfide 128 in

moderate yield (41) (Scheme 30) [115]The reaction conditions for the formation of the gem-

difluorides and trifluorides involved treating respective sub-strate 129 or 131 with AgBF

4(11 molar equiv per halide)


HO

11 equiv TMSOMe

Nitromethane120

121

122

10mol (S)-(xylyl-phanephos)PtI225mol AgBF4

30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H

Scheme 27 Catalytic cyclization and C3-fluorination of polyene

O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1

R1 + AgBr darr + BF3

R1 = R2ne H R3

ne Cl

Scheme 28 Synthesis of 120572-fluorocarbonyl compounds 124

Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙

Scheme 29 Proposed reaction mechanism for 120572-fluorocarbonylcompounds

PhSH

126127 128

PhSCF2Br PhS-CF3CH2Cl2 rt

AgBF4

Scheme 30 AgBF4-mediated synthesis of trifluoromethyl sulfide

130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4

R1R2CF2 + 2AgX2 + 2BF3 uarr


Scheme 31 Exchange-fluorination by reaction with AgBF4

in CH2Cl2for 1 hour at room temperature followed by

workup to obtain 35ndash84 yields (Scheme 31) Bloodworthet al suggested that the reactions proceeded via cationicintermediates as demonstrated by the proposed mechanismin Scheme 32 [116]

In another study [117] direct electrophilic fluorinationreaction of aryl silanes 138 with F-TEDA-BF

4139 catalyst

afforded less than 4 yield Not only did addition of AgBF4

to the reaction system improve the yield to 11 but alsoregiospecific fluorination was observed Intriguingly Ag(I)oxide was identified as the silver salt that resulted in thehighest yield of aryl fluoride (60ndash90) (Scheme 33)

C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136

Scheme 32 Mechanism of exchange-fluorination by reaction withAgBF

4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3

Scheme 33 Silver-mediated synthesis of 4-fluorobiphenyl

In addition to the reactivities of AgBF4described above

an effective electrophilic trifluoromethylating reagent being(trifluoromethyl)dibenzotellurophenium salt was developed[39 108] The experimental protocol aimed to afford the salt


Te Te Te

RHet

H RHet

DCETFA 10 equiv141142

143

144

145

BF minus4

15 equiv

++

Me2SOTf2O

Pd(OAc)2 (10mol)Cu(OAc)2 (100mol) 53ndash88

1( ) n-Bu4NBr(2) AgBF4

CF3

CF3CF3CF3TfOminus

Scheme 34 Synthesis of Umemoto reagent and ortho-trifluoromethylation of heterocycle-substituted arenes

RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl

+ Ac2O + NXBX = Cl Br I

Scheme 35 Highly regio- and stereoselective synthesis of (Z)-120573-haloenol acetates

OH

OH

X

Benzo[a]fluorenolBenzodiyne

148 149

AgBF4 (5mol)

DCM 10∘CX = I Br R2 R3

R2

R1

R1

R3 + NXS

Scheme 36 Synthesis of halo-substituted benzo[a]fluorenols

I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150

Electrophilicaddition

addition6-endo-electrophilic

Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus

Scheme 37 Mechanism for AgBF4-catalyzed sequential electrophilic cyclization reaction


consisting of treatment of telluride 141 with an equimolarmixture of triflic anhydride and DMSO at 0∘C followedby anion exchange with AgBF

4[118] Synthesized trifluo-

romethylated arenes 145 (53ndash88 yields) were obtained byreacting substituted arenes 144 with Umemoto reagents 143Pd(OAc)

2 and Cu(OAc)

2at 110∘C in a mixture of dichlo-

roethane (DCE) and 10 equiv of trifluoroacetic acid (TFA)(Scheme 34) [39]

The AgBF4activates alkyne moieties via 120587-complexes

as exemplified in the regio- and stereoselective difunctionalsynthesis of (Z)-120573-haloenol acetates from terminal alkynes(Scheme 35) [119] Interestingly reaction of phenylacetylene146 and N-halosuccinimide in acetic anhydride in the pres-ence of AgBF

4at 120∘C affords 60ndash90 yield of (Z)-120573-

haloenol acetate compounds 147These vinyl halides are thusimportant starting materials for transition-metal-catalyzedcross coupling reactions and halogen-metal exchange reac-tions [120]

Reports indicate that AgBF4and NXS catalysed electro-

philic cascade cyclization of halo-substituted benzo[a]flu-orenols 149 under mild conditions (Scheme 36) [38] Into aCH2Cl2(05mL)mixture ofN-iodosuccinimide (024mmol)

andAgBF4(001mmol) at 10∘C was added a CH

2Cl2(10mL)

solution of benzodiyne 148 (020mmol) under nitrogenAfter 12 h the reaction mixture was quenched with satu-rated ammonium chloride solution (3mL) and flash columnchromatography (ethyl acetaten-hexane 1 50) purificationafforded 149 (76) as a light yellow solid A plausible mech-anism is depicted in Scheme 37 The fused fluorenol deriva-tives 149 are well known to be widely applied in optoelec-tronic materials because of their highly conjugated rigidsystems They are extensively found as structural moietiesin numerous natural products such as kinamycin D recog-nised as 5-diazobenzo[b]fluorine a naturally occurring diazocompound that possesses antitumor properties and antibioticactivity against Gram-positive organisms [38]

7 Conclusions

Phytochemicals have generally been noted to exhibit impor-tant health effects such as anticancer antimicrobial antiox-idant antidiarrheal analgesic and wound healing actionsto humans and animals Accordingly a number of AgBF

4-

mediated syntheses of biologically active phytochemicalshave been described over the past six years in addition tothese there are those not reviewed in the previous reviews[40ndash43] Hence herein we reviewed the bioactivity andnatural occurrences of some phytochemicals synthesizedthroughAgBF

4-promoted reactions from 1979 when Fry and

Migron published its use in this regard until April 2014

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

Financial support from Research and Innovation Fund(33194351) of the Central University of Technology FreeState is hereby acknowledged with great appreciation

References

[1] P Cos A J Vlietinck D V Berghe and LMaes ldquoAnti-infectivepotential of natural products how to develop a stronger in vitrolsquoproof-of-conceptrsquordquo Journal of Ethnopharmacology vol 106 no3 pp 290ndash302 2006

[2] S Sasidharan Y Chen D Saravanan K M Sundram andL Y Latha ldquoExtraction isolation and characterization ofbioactive compounds from plantsrsquo extractsrdquo African Journal ofTraditional Complementary and Alternative Medicines vol 8no 1 pp 1ndash10 2011

[3] P F Surai ldquoNatural antioxidants in poultry nutrition newdevelopmentsrdquo in Proceedings of the 16th European Symposiumon Poultry Nutrition World Poultry Science Association Stras-boury France 2007

[4] R Puupponen-Pimia L Nohynek H-L Alakomi and K-M Oksman-Caldentey ldquoBioactive berry compoundsmdashnoveltools against human pathogensrdquo Applied Microbiology andBiotechnology vol 67 no 1 pp 8ndash18 2005

[5] A Samanta G Das and S K Das ldquoRoles of flavonoids inplantsrdquo International Journal of Pharmaceutical Science andTechnology vol 6 pp 12ndash35 2011

[6] WA Peer andA SMurphyTheScience of Flavonoids SpringerNew York NY USA 2006

[7] A Fawe M Abou-Zaid J G Menzies and R R BelangerldquoSilicon-mediated accumulation of flavonoid phytoalexins incucumberrdquo Phytopathology vol 88 no 5 pp 396ndash401 1998

[8] D J McNally K V Wurms C Labbe and R R BelangerldquoSynthesis of C-glycosyl flavonoid phytoalexins as a site-specificresponse to fungal penetration in cucumberrdquo Physiological andMolecular Plant Pathology vol 63 no 6 pp 293ndash303 2003

[9] H Yamasaki Y Sakihama and N Ikehara ldquoFlavonoid-peroxidase reaction as a detoxificationmechanism of plant cellsagainst H

2O2rdquo Plant Physiology vol 115 no 4 pp 1405ndash1412

1997[10] M A K Jansen R E van den Noort M Y Adillah Tan E

Prinsen L M Lagrimini and R N F Thorneley ldquoPhenol-oxidizing peroxidases contribute to the protection of plantsfrom ultraviolet radiation stressrdquo Plant Physiology vol 126 no3 pp 1012ndash1023 2001

[11] AMichalak ldquoPhenolic compounds and their antioxidant activ-ity in plants growing under heavy metal stressrdquo Polish Journalof Environmental Studies vol 15 no 4 pp 523ndash530 2006

[12] S Bagga and D Straney ldquoModulation of cAMP and phosphodi-esterase activity by flavonoids which induce spore germinationof Nectria haematococca MP VI (Fusarium solani)rdquo Physiologi-cal andMolecular Plant Pathology vol 56 no 2 pp 51ndash61 2000

[13] D Morandi B Branzanti and V Gianinazzi-Pearson ldquoEffect ofsome plant flavonoids on in vitro behaviour of an arbuscularmycorrhizal fungusrdquo Agronomie vol 12 no 10 pp 811ndash8161992

[14] B W Shirley ldquoFlavonoids in seeds and grains physiologicalfunction agronomic importance and the genetics of biosynthe-sisrdquo Seed Science Research vol 8 no 4 pp 415ndash422 1998


[15] K S Gould and C Lister ldquoFlavonoid functions in plantsrdquo inFlavonoids Oslash M Andersen and K R Markham Eds pp 397ndash442 CRC Press Boca Raton Fla USA 2006

[16] A Lanot and P Morris ldquoElicitation of isoflavan phytoalexinsrdquoin Lotus Japonicus Handbook A J Marquez Ed pp 355ndash361Springer Amsterdam The Netherlands 2005

[17] F D Vergas and O P Lopez Natural Colorants for Food andNutraceutical Uses CRC Press New York NY USA 2003

[18] F Kaplan J Kopka D W Haskell et al ldquoExploring thetemperature-stress metabolome of Arabidopsisrdquo Plant Physiol-ogy vol 136 no 4 pp 4159ndash4168 2004

[19] I Hernandez L Alegre and S Munne-Bosch ldquoDrought-induced changes in flavonoids and other low molecular weightantioxidants in Cistus clusii grown under Mediterranean fieldconditionsrdquo Tree Physiology vol 24 no 11 pp 1303ndash1311 2004

[20] T Iwashina ldquoFlavonoid function and activity to plants andotherorganismsrdquo Biological Sciences in Space vol 17 no 1 pp 24ndash442003

[21] A P Mamolos and K L Kalburtji ldquoSignificance of allelopathyin crop rotationrdquo in Allelopathy in Agroecosystems pp 197ndash218Food Products Press Binghamton NY USA 2001

[22] S O Duke ldquoThe emergence of grass root chemical ecologyrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 104 no 43 pp 16729ndash16730 2007

[23] M C AchilonuNovel synthetic approaches toward procyanidinsand bioflavonoids [PhD thesis] University of the Free StateBloemfontein South Africa 2009

[24] V Kren and L Martınkove ldquoGlycosides in medicine the roleof glycosidic residue in biological activityrdquo Current MedicinalChemistry vol 8 no 11 pp 1303ndash1328 2001

[25] C Spanou G Bourou A Dervishi et al ldquoAntioxidantand chemopreventive properties of polyphenols compoundsderived from Greek legume plant extractsrdquo Journal of Agricul-tural and Food Chemistry vol 56 no 16 pp 6967ndash6976 2008

[26] J C Mathers ldquoPulses and carcinogenesis potential for theprevention of colon breast and other cancersrdquo British Journalof Nutrition vol 88 no 3 pp S273ndashS279 2002

[27] L H Kushi K AMeyer and D R Jacobs Jr ldquoCereals legumesand chronic disease risk reduction evidence from epidemio-logic studiesrdquo The American Journal of Clinical Nutrition vol70 no 3 pp 451ndash458 1999

[28] C Spanou A S Veskoukis T Kerasioti et al ldquoFlavonoidglycosides isolated from unique legume plant extracts as novelinhibitors of xanthine oxidaserdquo PLoS ONE vol 7 no 3 ArticleID e32214 2012

[29] W C Evans ldquoPharmacopoeial and related drugs of biologicalorigin Alkaloidsrdquo in Trease and EvansPharmacognosy G ETrease and W C Evans Eds WB Saunders London UK 14thedition 1996

[30] G C L Ee CM LimM Rahmani K Shaari and C F J BongldquoPellitorine a potential anti-cancer lead compound againstHL60 and MCT-7 cell lines and microbial transformation ofpiperine from Piper nigrumrdquoMolecules vol 15 no 4 pp 2398ndash2404 2010

[31] T M Godlaski ldquoGods of drugs the God withinrdquo Substance Useand Misuse vol 46 no 10 pp 1217ndash1222 2011

[32] L Xia Y R Lee S H Kim andW S Lyoo ldquoAgBF4[Bmim]BF

4-

Catalyzed [3+2] cycloaddition of cyclic diazodicarbonyl com-pounds efficient synthesis of 23-dihydrofurans and conversionto 3-acylfuransrdquo Bulletin of the Korean Chemical Society vol 32no 5 pp 1554ndash1558 2011

[33] F M Dean ldquoRecent advances in furan chemistryrdquo in Advancesin Heterocyclic Chemistry A R Katritzky Ed vol 30 pp 167ndash238 Academic Press New York NY USA 1982

[34] F M Dean and M V Sargent Comprehensive HeterocyclicChemistry vol 4 of edited by C W Bird G W H Cheesemanpart 3 Pergamon New York NY USA 1984

[35] K Nakanishi Natural Products Chemistry Kodansha TokyoJapan 1974

[36] GVernin andGM FVernin ldquoHeterocyclic aroma compoundsin foods occurrence and organoleptic propertiesrdquo in Chemistryof Heterocyclic Flavoring and Aroma Compounds G Vernin andC Parkanyi Eds pp 72ndash150 Ellis Horwood Chichester UK1982

[37] G Schulte P J Scheuer and O J McConnell ldquoTwo fura-nosesquiterpene marine metabolites with antifeedant proper-tiesrdquo Helvetica Chimica Acta vol 63 no 8 pp 2159ndash2167 1980

[38] Z Chen M Zeng J Yuan Q Yang and Y Peng ldquoNovel silvertetrafluoroborate catalyzed electrophilic cascade cyclizationreaction a facile approach to the synthesis of halo-substitutedbenzo[a]fluorenolsrdquo Organic Letters vol 14 no 14 pp 3588ndash3591 2012

[39] N Shibata A Matsnev and D Cahard ldquoShelf-stable elec-trophilic trifluoromethylating reagents a brief historical per-spectiverdquo Beilstein Journal of Organic Chemistry vol 6 no 6519 pages 2010

[40] M Alvarez-Corral M Munoz-Dorado and I Rodrıguez-Garcıa ldquoSilver-mediated synthesis of heterocyclesrdquo ChemicalReviews vol 108 no 8 pp 3174ndash3198 2008

[41] Z Li and C He ldquoRecent advances in silver-catalyzed nitrenecarbene and silylene-transfer reactionsrdquo European Journal ofOrganic Chemistry vol 2006 no 19 pp 4313ndash4322 2006

[42] J-M Weibel A Blanc and P Pale ldquoAg-mediated reactionscoupling and heterocyclization reactionsrdquo Chemical Reviewsvol 108 no 8 pp 3149ndash3173 2008

[43] P Belmont ldquoSilver-catalyzed cycloisomerization reactionsrdquo inSilver in Organic Chemistry M Harmata Ed pp 143ndash165 JohnWiley amp Sons Hoboken NJ USA 2010

[44] G Abbiati and E Rossi ldquoSilver and gold-catalyzedmulticompo-nent reactionsrdquo Beilstein Journal of Organic Chemistry vol 10pp 481ndash513 2014

[45] J Zeng Y Bai S Cai J Ma and X-W Liu ldquoDirect synthesisof pyrroles via a silver-promoted three-component reactioninvolving unusual imidazole ring openingrdquo Chemical Commu-nications vol 47 no 48 pp 12855ndash12857 2011

[46] L J Porter The Flavonoids Advances in Research Since 1986edited by J B Harborne Chapman amp Hall London UK 1994

[47] B Tanwar and R Modgil ldquoFlavonoids dietary occurrence andhealth benefitsrdquo Spatula DD vol 2 no 1 pp 59ndash68 2012

[48] J W T Selway ldquoAntiviral activity of flavones and flavansrdquoin Plant Flavonoids in Biology and Medicine BiochemicalPharmacological and Structure Activity Relationships V CodyEMiddleton and J BHarborne Eds pp 521ndash536 AlanR LissNew York NY USA 1986

[49] P J Steynberg R J J Nel H Van Rensburg B C BBezuidenhoudt and D Ferreira ldquoOligomeric flavanoids Part27 Interflavanyl bond formation in procyanidins under neutralconditionsrdquo Tetrahedron vol 54 no 28 pp 8153ndash8158 1998

[50] A P Kozikowski W Tuckmantel G Bottcher and L JRomanczyk Jr ldquoStudies in polyphenol chemistry and bioac-tivity 4 Synthesis of trimeric tetrameric pentameric and


higher oligomeric epicatechin-derived procyanidins having all-41205738-interflavan connectivity and their inhibition of cancercell growth through cell cycle arrestrdquo The Journal of OrganicChemistry vol 68 no 5 pp 1641ndash1658 2003

[51] L Bennie E Malan J Coetzee and D Ferreira ldquoStructure andsynthesis of ether-linked proteracacinidin and promelacacini-din proanthocyanidins fromAcacia caffrardquo Phytochemistry vol53 no 7 pp 785ndash793 2000

[52] M C Achilonu S L Bonnet and J H van der WesthuizenldquoSynthesis of proanthocyanidins Part 1 The first oxidativeformation of the interflavanyl bond in procyanidinsrdquo OrganicLetters vol 10 no 17 pp 3865ndash3868 2008

[53] P Pornsuriyasak and A V Demchenko ldquoS-thiazolinyl (STaz)glycosides as versatile building blocks for convergent selec-tive chemoselective and orthogonal oligosaccharide synthesisrdquoChemistry vol 12 no 25 pp 6630ndash6646 2006

[54] S Kaeothip P Pornsuriyasak and A V Demchenko ldquoSilver(I)tetrafluoroborate as a potent promoter for chemical glycosyla-tionrdquo Tetrahedron Letters vol 49 no 9 pp 1542ndash1545 2008

[55] W Liu H Jiang and L Huang ldquoOne-pot silver-catalyzed andPIDA-mediated sequential reactions synthesis of polysubsti-tuted pyrroles directly from alkynoates and aminesrdquo OrganicLetters vol 12 no 2 pp 312ndash315 2010

[56] G Buscemi A Biffis C Tubaro M Basato C Graiff and ATiripicchio ldquoC-H bond functionalization of aromatic heterocy-cles with chelating dicarbene palladium (II) and platinum (II)complexesrdquoAppliedOrganometallic Chemistry vol 24 no 4 pp285ndash290 2010

[57] H Hart L E Craine andD J HartOrganic Chemistry A ShortCourse Houghton Mifflin Company Boston Mass USA 1999

[58] C A Broka and J F Gerlits ldquoAziridinium cation mediatedcyclizations New routes to themorphinan ring systemrdquo Journalof Organic Chemistry vol 53 no 10 pp 2144ndash2150 1988

[59] R A Morton Biochemistry of Quinones Academic Press NewYork NY USA 1965

[60] R HThomsonNaturally Occurring Quinones Academic PressNew York NY USA 2nd edition 1971

[61] J S Driscoll G F Hazard Jr H B Wood Jr and A GoldinldquoStructure-antitumor activity relationships among quinonederivativesrdquo Cancer Chemotherapy Reports Part 2 vol 4 no 2pp 1ndash362 1974

[62] MRamesh P SMohan andP Shanmugam ldquoA convenient syn-thesis of flindersine atanine and their analoguesrdquo Tetrahedronvol 40 no 20 pp 4041ndash4049 1984

[63] K M Witherup R W Ransom S L Varga S M PitzenbergerV J Lotti and W J Lumma ldquoPyrroloquinoline bradykininantagonistrdquo US Patent 5288725 1994

[64] N B Perry J W Blunt J D McCombs and M H MunroldquoDiscorhabdin C a highly cytotoxic pigment from a sponge ofthe genus Latrunculiardquo Journal of Organic Chemistry vol 51 no26 pp 5476ndash5478 1986

[65] N M Williamson D R March and A D Ward ldquoAn im-proved synthesis of 22-disubstituted-12-dihydroquinolinesand their conversion to 3-chloro-22-disubstituted-tetrahydro-quinolinesrdquo Tetrahedron Letters vol 36 no 42 pp 7721ndash77241995

[66] N Yamada S Kadowaki K Takahashi and K Umezu ldquoMY-1250 a major metabolite of the anti-allergic drug repirinastinduces phosphorylation of a 78-kDa protein in rat mast cellsrdquoBiochemical Pharmacology vol 44 no 6 pp 1211ndash1213 1992

[67] K Faber H Stuckler and T Kappe ldquoNon-steroidal anti-inflammatory agents 1 Synthesis of 4-hydroxy-2-oxo-12-dihydroquinolin-3-yl alkanoic acids by the wittig reaction ofquinisatinesrdquo Journal of Heterocyclic Chemistry vol 21 no 4pp 1177ndash1181 1984

[68] Y Luo Z Li and C-J Li ldquoA silver-catalyzed domino routetoward 12-dihydroquinoline derivatives from simple anilinesand alkynesrdquoOrganic Letters vol 7 no 13 pp 2675ndash2678 2005

[69] R-Y Tang P-S Luo X-G Zhang P Zhong and J-HLi ldquoSilver-catalyzed tandem ammonolysis-cyclization of 2-alkynylbenzenamines with tetraalkylthiuram disulfides to 4-methylene-4 h -benzo[d][13]thiazin-2-aminesrdquo Synlett no 9pp 1345ndash1350 2010

[70] M G Banwell J E Harvey and K A Jolliffe ldquo120587-Allyl cationcyclisations initiated by electrocyclic ring-opening of gem-dihalocyclopropanes application to the first total syntheses ofthe crinine-type alkaloidsmaritinamine and epi-maritinaminerdquoJournal of the Chemical Society Perkin Transactions 1 no 17 pp2002ndash2005 2001

[71] M A Schwartz and R A Holton ldquoIntramolecular oxida-tive phenol coupling II Biogenetic-type synthesis of (+-)-maritidinerdquo Journal of the American Chemical Society vol 92no 4 pp 1090ndash1092 1970

[72] H Irie S Uyeo and A Yoshitake ldquoThe total synthesis of dihy-drocrinine and related compoundsrdquo Journal of the ChemicalSociety C Organic vol 14 pp 1802ndash1804 1968

[73] H Muxfeldt R S Schneider and J B Mooberry ldquoA totalsynthesis of (plusmn)-crininerdquo Journal of the American ChemicalSociety vol 88 no 15 pp 3670ndash3671 1966

[74] H W Whitlock Jr and G L Smith ldquoTotal synthesis of dl-crininerdquo Journal of the American Chemical Society vol 89 no14 pp 3600ndash3606 1967

[75] R V Stevens ldquoGeneral methods of alkaloid synthesisrdquoAccountsof Chemical Research vol 10 no 6 pp 193ndash198 1977

[76] J B P A Wijnberg and W N Speckamp ldquoTotal syn-theses of dl-mesembrine dl-dihydromaritidine and dl-epi-dihydromaritidine via regioselective NaBH

4H+ reduction of

imidesrdquo Tetrahedron vol 34 no 16 pp 2579ndash2586 1978[77] G E Keck and R R Webb II ldquoAlkaloid synthesis via

intramolecular ene reaction 2 Application to dl-mesembrineand dl-dihydromaritidinerdquo Journal of Organic Chemistry vol47 no 7 pp 1302ndash1309 1982

[78] I H Sanchez F J Lopez H J Flores and M I Larraza ldquoNovelconformational effects of theN-benzyloxycarbonyl-cis-3a-aryl-octahydroindole nucleus Formal total synthesis of racemicelwesine and epielwesinerdquo Heterocycles vol 20 no 2 pp 247ndash254 1983

[79] S F Martin and C L Campbell ldquoTotal syntheses of (plusmn)-crinineand (plusmn)-buphanisinerdquo Journal of Organic Chemistry vol 53 no14 pp 3184ndash3190 1988

[80] J P Michael A S Howard R B Katz and M I Zwane ldquoFor-mal syntheses of (plusmn)-mesembrine and (plusmn)-dihydromaritidinerdquoTetrahedron Letters vol 33 no 40 pp 6023ndash6024 1992

[81] R M Burk and L E Overman ldquoTotal synthesis of the Amaryll-idaceae alkaloid (plusmn)-epielwesine The importance of vinylsilanestereochemistry in iminium ion-vinylsilane cyclizationsrdquoHete-rocycles vol 35 no 1 pp 205ndash225 1993

[82] W H Pearson and F E Lovering ldquoAssembly of 3120572-arylperhy-droindoles by the intramolecularcycloaddition of 2-azaallyl ani-ons with alkenes Total syntheses of (plusmn)-crinine (plusmn)-6-epicri-nine (minus)-amabiline and (minus)-augustaminerdquo Journal of OrganicChemistry vol 63 no 11 pp 3607ndash3617 1998


[83] A Padwa M A Brodney M Dimitroff B Liu and T WuldquoApplication of furanyl carbamate cycloadditions toward thesynthesis of hexahydroindolinone alkaloidsrdquo Journal of OrganicChemistry vol 66 no 9 pp 3119ndash3128 2001

[84] Y R Lee and J H Choi ldquoRh2(Opiv)4-catalyzed reactions of

diazo compound derived from Meldrumrsquos acid and styrenesEfficient synthesis of cyclopropanesrdquo Bulletin of the KoreanChemical Society vol 27 no 4 pp 503ndash507 2006

[85] M G Banwell ldquoNew processes for the synthesis of biologicallyrelevant heterocyclesrdquo Pure and Applied Chemistry vol 80 no4 pp 669ndash679 2008

[86] PA Suryavanshi V Sridharan and J CMenendez ldquoExpedientone-pot preparation of fused indoles via CAN-catalyzed three-component domino sequences and their transformation intopolyheterocyclic compounds containing pyrrolo[12-a]azepinefragmentsrdquoOrganicampBiomolecular Chemistry vol 8 no 15 pp3426ndash3436 2010

[87] T Aniszewski ldquoAlkaloidsmdashsecrets of liferdquo in Alkaloid Chem-istry Biological Significance Applications and Ecological Role p112 Elsevier Amsterdam The Netherlands 2007

[88] A C Shaikh and C Chen ldquoAn easy and efficient synthesisof bisindolylmethanes and tetraindolylmethane Trogerrsquos basecatatlyzed by AgBF

4rdquo Journal of the Chinese Chemical Society

vol 58 no 7 pp 899ndash905 2011[89] H-M Ko K K-Y Kung J-F Cui and M-K Wong ldquoBis-

cyclometallated gold(III) complexes as efficient catalysts forsynthesis of propargylamines and alkylated indolesrdquo ChemicalCommunications vol 49 no 78 pp 8869ndash8871 2013

[90] D S Grierson J-L Bettiol I Buck H-P Husson M Rubiraltaand A Diez ldquoSynthesis of 20-deethylsilicine from a second-generation 2-cyano-9987793-piperidine synthonrdquo Journal of OrganicChemistry vol 57 no 24 pp 6414ndash6421 1992

[91] M E Kuehne and IMarkoTheAlkaloids vol 37 of edited by ABrossi M Suffness Academic Press New York NY USA 1990

[92] A U Basha A Basha and M Ghazala ldquoSynthetic studies ofanti-leukaemic alkaloids VII the partial synthesis of vinblas-tinerdquo Tetrahedron Letters vol 17 pp 2351ndash2354 1976

[93] G A Cordell Heterocyclic Compounds The MonoterpenoidIndole Alkaloids vol 25 John Wiley amp Sons New York NYUSA 1983 edited by J E Saxton

[94] M Lounasmaa and A Nemes ldquoThe synthesis of bis-indolealkaloids and their derivativesrdquo Tetrahedron vol 38 no 2 pp223ndash243 1982

[95] M E Kuehne P A Matson and W G Bornmann ldquoEnantios-elective syntheses of vinblastine leurosidine vincovaline and201015840-epi-vincovalinerdquo Journal of Organic Chemistry vol 56 no2 pp 513ndash528 1991

[96] A Padwa andM Ishida ldquoSilver tetrafluoroborate induced reac-tion of trimethylsilyl enol ethers with 23-diiodo-1-(phenylsul-fonyl)-1-propene as a method for preparing substituted furansrdquoTetrahedron Letters vol 32 no 41 pp 5673ndash5676 1991

[97] W H Lewis and M P F Elvin-Lewis Medical Botany JohnWiley amp Sons New York NY USA 1977

[98] G W Gribble ldquoOccurence of halogenated alkaloidsrdquo TheAlkaloids Chemistry and Biology vol 71 pp 1ndash165 2012

[99] T Yamazaki T Taguchi and I Ojima ldquoIntroduction basicaspects of fluorine in chemistry and biologyrdquo in Fluorine inMedicinal Chemistry and Chemical Biology I Ojima Ed pp1ndash47 Wiley-Blackwell London UK 2009

[100] P KirschModern Fluoroorganic Chemistry Wiley-VCHWein-heim Germany 2004

[101] S J Gould C RMelville M C Cone J Chen and J R CarneyldquoKinamycin biosynthesis Synthesis isolation and incorpo-ration of stealthin C an aminobenzo[b]fluorenerdquo Journal ofOrganic Chemistry vol 62 no 2 pp 320ndash324 1997

[102] S J Gould N Tamayo C R Melville and M C ConeldquoRevised structures for the kinamycin antibiotics 5-diazoben-zo[b]fluorenes rather than benzo[b]carbazole cyanamidesrdquoJournal of the American Chemical Society vol 116 no 5 pp2207ndash2208 1994

[103] S Mithani G Weeratunga N J Taylor and G I DmitrienkoldquoThe kinamycins are diazofluorenes and not cyanocarbazolesrdquoJournal of the American Chemical Society vol 116 no 5 pp2209ndash2210 1994

[104] S Omura A Nakagawa H Yamada T Hata A Furusaki andTWatanabe ldquoStructures and biological properties of kinamycinA B C and Drdquo Chemical and Pharmaceutical Bulletin vol 21no 5 pp 931ndash940 1973

[105] A Furusaki M Matsui T Watanabe S Omura A Nakagawaand T Hata ldquoThe crystal and molecular structure of kinamycinC-p-bromo-benzoaterdquo Israel Journal of Chemistry vol 10 no 2pp 173ndash187 1972

[106] J-P Begue and D Bonnet-Delpon Bioorganic and MedicinalChemistry of Fluorine John Wiley amp Sons Hoboken NJ USA2008

[107] N A Cochrane H Nguyen and M R Gagne ldquoCatalyticenantioselective cyclization and C3-fluorination of polyenesrdquoJournal of the American Chemical Society vol 135 no 2 pp628ndash631 2013

[108] K-P Wang S Y Yun P Mamidipalli and D Lee ldquoSilver-mediated fluorination trifluoromethylation and trifluoro-methylthiolation of arynesrdquo Chemical Science vol 4 no 8 pp3205ndash3211 2013

[109] K Muller C Faeh and F Diederich ldquoFluorine in pharmaceu-ticals looking beyond intuitionrdquo Science vol 317 no 5846 pp1881ndash1886 2007

[110] H-J Bohm D Banner S Bendels et al ldquoFluorine in medicinalchemistryrdquo ChemBioChem vol 5 no 5 pp 637ndash643 2004

[111] C Isanbor and D OrsquoHagan ldquoFluorine in medicinal chemistrya review of anti-cancer agentsrdquo Journal of Fluorine Chemistryvol 127 no 3 pp 303ndash319 2006

[112] D OrsquoHagan and D B Harper ldquoThe fluorinated natural prod-uctsrdquo Natural Product Reports vol 11 no 2 pp 123ndash133 1994

[113] C D Murphy C Schaffrath and D OrsquoHagan ldquoFluorinatednatural products the biosynthesis of fluoroacetate and 4-fluorothreonine in Streptomyces cattleyardquo Chemosphere vol 52no 2 pp 455ndash461 2003

[114] A J Fry and Y Migron ldquoA convenient new synthesis of 120572-fluorocarbonyl compoundsrdquoTetrahedron Letters vol 20 no 36pp 3357ndash3360 1979

[115] M Suda and C Hino ldquoPreparation of bromodifluoromethylsulfide and its conversion to trifluoromethyl sulfiderdquo Tetrahe-dron Letters vol 22 no 21 pp 1997ndash2000 1981

[116] A J Bloodworth K J Bowyer and J C Mitchell ldquoA mildconvenient halogen-exchange route to gem-difluorides andtrifluoridesrdquo Tetrahedron Letters vol 28 no 44 pp 5347ndash53501987

[117] P Tang and T Ritter ldquoSilver-mediated fluorination of arylsilanesrdquo Tetrahedron vol 67 no 24 pp 4449ndash4454 2011

[118] T Umemoto and S Ishihara ldquoPower-variable electrophilictrifluoromethylating agents S- Se- andTe-(trifluoromethyl)di-benzothio- -seleno- and -tellurophenium salt systemrdquo Journal


of the American Chemical Society vol 115 no 6 pp 2156ndash21641993

[119] Z Chen J Li H Jiang S Zhu Y Li and C Qi ldquoSilver-catalyzeddifunctionalization of terminal alkynes highly regio- andstereoselective synthesis of (Z)-120573-Haloenol acetatesrdquo OrganicLetters vol 12 no 14 pp 3262ndash3265 2010

[120] X Chen D Chen Z Lu L Kong and G Zhu ldquoPalladium-catalyzed coupling of haloalkynes with allyl acetate a regio- andstereoselective synthesis of (Z)-120573-haloenol acetatesrdquo Journal ofOrganic Chemistry vol 76 no 15 pp 6338ndash6343 2011

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


OHO

OH

A C B OHO

OH O

OHO

HOHO HO

OH OOH

OH

OH OHOH

OH

OHOH

OH

OH

O

O

O O

1

2

3

456

78

Flavanone 4 Flavanol 5 Anthocyanidin 6

Base structure 1 Flavone 2 Flavonol 3

6998400 5998400

4998400

39984002998400

+

Figure 1 Base structure and subgroups of flavonoids

OO

OH

OH

OH

O O OHOH

HO

O

O OHOHOH

OHO

HO

OHO

O

O

O

OHO

OH

OMe

OHOH

O

O O

OHHO

HOOH

HO

HOHO

OHO

OH

OH

OMe

O

Glc Glc

CAF

CAF

Glc

Glc

CAF

Glc

7

8

Heavy blue anthocyanidin(peonidin acyl-glycoside)

Quercetin 3-O-rhamnopyranosyl(1rarr2)-

+

= 120573-maltoside 10R1 = H = Silybin 9

CH2OR1

R1

glucopyranoside-7-Orhamnopyranoside

Figure 2 Natural polyphenolic flavonoid glycosides

forth [24] Literature revealed that amongst these glycosidesare a range of natural polyphenolic flavonoid glycosidesrichly found in legume plants (Figure 2) [25ndash28]

Typical alkaloidsmainly derived fromplant sources are alarge group of secondarymetabolites containing usually basicnitrogen in a heterocycle which are broadly varied in chem-ical structure and in pharmacological action (Figure 3) [29]The toxicity of some alkaloids is widely recognized however

they are a source of many biologically active phytochemicalswith great potential formedicinal and agricultural usesManyalkaloids have attractive pharmacological effects and are usedas medications such as recreational drugs or in entheogenicrituals [30 31]

Furans particularly 23-dihydrofurans are one of theabundant structural motifs found in plants that possessimpressive biological activities and as a result are extensively


NH

NN N

H






4




4-mediated




4mediation are




4-mediated reac-



2 Proanthocyanidins




4towards oxygen









4for 90min under





O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

15

16

17

Procyanidin B-1

+

SCH2Ph

AgBF4 in THF

0∘C 1h


S N

O

OHS

BnO

OBn

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

O

OBn

OBn

OBn

BnO

OH

O

O

BnO OBn

OBn

O

HO

OBn

BnO

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

OBn

OBn

OBn

O

OH

BnO

OBnO

OBn

OBn

OBn

BnO

OHO

OH

BnO

OBn

OBn

OBn

18

21

19

20

22

AgBF4

THF 0∘C

+




The BF4


3 Glycosides



O

O

O

O

O

O

O

O

O

O

+

26

27

23

OAcOAcOAc

OAc

OAc

OAc

OAcOAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

AcOAcO

AcO

AcO

AcO

AcO

AcO

AcO

AcOHO

HO

OH

OH

OH

OH

OHOH

OH

OH24

(1) AgBF4THF

(2) PyAc2O

25


OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

O

OMeO

MeO

MeO

MeO O

O

O

O

28

+

2930

31

OH

OH

AgBF4 THF

Reflux 4h

30 (38) 31 (6)





O

O

O

O

O

O

H

O

O

O

O

BO

O

D

CA

O

O

O

O28 32

33

34

35

3637

3839

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe OMe

OMe

OMe

OMe

OMe

OMe

OMe

MeO MeOMeO

MeO

MeOMeO

MeO

MeO

MeO

MeO

MeO

minusBF4

minusBF4

Ag+minuse 1

Ag+minuse 1

+

+

+

+

minusH+

minusH+

∙+

∙

∙∙






4 Alkaloids



O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe










4-catalyzed and




N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


NH

NN N

H






4




4-mediated




4mediation are




4-mediated reac-



2 Proanthocyanidins




4towards oxygen









4for 90min under





O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

15

16

17

Procyanidin B-1

+

SCH2Ph

AgBF4 in THF

0∘C 1h


S N

O

OHS

BnO

OBn

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

O

OBn

OBn

OBn

BnO

OH

O

O

BnO OBn

OBn

O

HO

OBn

BnO

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

OBn

OBn

OBn

O

OH

BnO

OBnO

OBn

OBn

OBn

BnO

OHO

OH

BnO

OBn

OBn

OBn

18

21

19

20

22

AgBF4

THF 0∘C

+




The BF4


3 Glycosides



O

O

O

O

O

O

O

O

O

O

+

26

27

23

OAcOAcOAc

OAc

OAc

OAc

OAcOAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

AcOAcO

AcO

AcO

AcO

AcO

AcO

AcO

AcOHO

HO

OH

OH

OH

OH

OHOH

OH

OH24

(1) AgBF4THF

(2) PyAc2O

25


OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

O

OMeO

MeO

MeO

MeO O

O

O

O

28

+

2930

31

OH

OH

AgBF4 THF

Reflux 4h

30 (38) 31 (6)





O

O

O

O

O

O

H

O

O

O

O

BO

O

D

CA

O

O

O

O28 32

33

34

35

3637

3839

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe OMe

OMe

OMe

OMe

OMe

OMe

OMe

MeO MeOMeO

MeO

MeOMeO

MeO

MeO

MeO

MeO

MeO

minusBF4

minusBF4

Ag+minuse 1

Ag+minuse 1

+

+

+

+

minusH+

minusH+

∙+

∙

∙∙






4 Alkaloids



O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe










4-catalyzed and




N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

O

OH

HO

OH

OH

OH

15

16

17

Procyanidin B-1

+

SCH2Ph

AgBF4 in THF

0∘C 1h


S N

O

OHS

BnO

OBn

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

O

OBn

OBn

OBn

BnO

OH

O

O

BnO OBn

OBn

O

HO

OBn

BnO

OBn

OBn

O

OH

BnO

OBn

OBn

OBn

OBn

OBn

OBn

O

OH

BnO

OBnO

OBn

OBn

OBn

BnO

OHO

OH

BnO

OBn

OBn

OBn

18

21

19

20

22

AgBF4

THF 0∘C

+




The BF4


3 Glycosides



O

O

O

O

O

O

O

O

O

O

+

26

27

23

OAcOAcOAc

OAc

OAc

OAc

OAcOAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

AcOAcO

AcO

AcO

AcO

AcO

AcO

AcO

AcOHO

HO

OH

OH

OH

OH

OHOH

OH

OH24

(1) AgBF4THF

(2) PyAc2O

25


OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

O

OMeO

MeO

MeO

MeO O

O

O

O

28

+

2930

31

OH

OH

AgBF4 THF

Reflux 4h

30 (38) 31 (6)





O

O

O

O

O

O

H

O

O

O

O

BO

O

D

CA

O

O

O

O28 32

33

34

35

3637

3839

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe OMe

OMe

OMe

OMe

OMe

OMe

OMe

MeO MeOMeO

MeO

MeOMeO

MeO

MeO

MeO

MeO

MeO

minusBF4

minusBF4

Ag+minuse 1

Ag+minuse 1

+

+

+

+

minusH+

minusH+

∙+

∙

∙∙






4 Alkaloids



O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe










4-catalyzed and




N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

O

O

O

O

O

O

O

O

+

26

27

23

OAcOAcOAc

OAc

OAc

OAc

OAcOAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

OAc

AcOAcO

AcO

AcO

AcO

AcO

AcO

AcO

AcOHO

HO

OH

OH

OH

OH

OHOH

OH

OH24

(1) AgBF4THF

(2) PyAc2O

25


OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

O

OMeO

MeO

MeO

MeO O

O

O

O

28

+

2930

31

OH

OH

AgBF4 THF

Reflux 4h

30 (38) 31 (6)





O

O

O

O

O

O

H

O

O

O

O

BO

O

D

CA

O

O

O

O28 32

33

34

35

3637

3839

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe OMe

OMe

OMe

OMe

OMe

OMe

OMe

MeO MeOMeO

MeO

MeOMeO

MeO

MeO

MeO

MeO

MeO

minusBF4

minusBF4

Ag+minuse 1

Ag+minuse 1

+

+

+

+

minusH+

minusH+

∙+

∙

∙∙






4 Alkaloids



O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe










4-catalyzed and




N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

O

O

O

O

H

O

O

O

O

BO

O

D

CA

O

O

O

O28 32

33

34

35

3637

3839

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe

OMe OMe

OMe

OMe

OMe

OMe

OMe

OMe

MeO MeOMeO

MeO

MeOMeO

MeO

MeO

MeO

MeO

MeO

minusBF4

minusBF4

Ag+minuse 1

Ag+minuse 1

+

+

+

+

minusH+

minusH+

∙+

∙

∙∙






4 Alkaloids



O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe










4-catalyzed and




N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

OH

S

S

N

O

OO

O

NIS O

OH

O

OO

OO

4140

43

44

42SEt

OBz

OBzOBz

OBz

OBz

OBz

OBz

OBz

OBz

BzO

BzOBzO

BzOBzO

BzO

BzOBzOBzO

BzO

BzO

BzO

DonorAcceptor

SEt

AgBF4

BnOBnO

BnO

BnOBnOBnO

OMe

OMe










4-catalyzed and




N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


N Ph N

Ph

HMe

L =

4546

48

47

+


Me

2mmol

1mmol HOAcCO2Et

CO2Et

L-AgBF4

25∘C

Z = 50

E = 50

N

N

Pd

N

N

MeMe Br Br


R N R+ +

49 50

51

52

PIDA (12 equiv)

CO2R2CO2R4

AgBF4 (5mol)

R1

R3

R1

R3


H2N

CO2R4







2Cl2) (Scheme 10)




4

(97mg 005mmol) HBF4








Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Ag

Ag

H

Ag

NRI

Ph

NR

I

Ph

H

NR

I

Ph

NR

H

Ag

H

NI

OAcR

Ph

N AgR

I

Ph

NR

43

54

5556

57

58 5960

6162

52

50

4953

R1

R3

R3

R1R1

R1

R1

R1

R1

R1

R1R1

R3 R3 R3

R3R3

R1 R1AgBF4

R2O2C

CO2R2

CO2R2

CO2R2

CO2R4

CO2R2CO2R2

CO2R2

CO2R2CO2R2CO2R2

CO2R4

CO2R4

CO2R4 CO2R4

CO2R4CO2R4

CO2R2

CO2R2

R

R

NH2

NH2

RHNRH2N

minusHOAc

PhI(OAc)2

HOAc

AcO AcOAcO

minusH

minusHAcO

minusPHI

ndashOAc

∙∙


ClO

6463TBDMSO

MeNNMe

56AgBF4 toluene


NH

H

HH

65 66

67


CH3NH2+



NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


NH

N

NH

H

H

H

N

H

H

+

65 66 68

65

69

Cyclization Cat65

6770

CH3

CH3

CH3

NH2


N SS N

S

SN

S

N+R1

R1

R2

R2

R3

R3

R3

R3

R3

R3AgBF4

NH2

7271 73

DMSO 80∘C












NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


NH

NH

H

NH

N

MeO

HO

OH

H

+

Cl

Cl

NH

ClClCl

Boc

MeO

OiPr74

AgBF4

THF 40∘C

OiPr

MeO

76

MeO

HO

OH

Boc

OiPr

MeO

75



Et3N

minus(Boc) 2O

minusHCl

∙∙
















4 The


5 Furans





2CO3 AgNO

3 AgClO

4 and AgOSO

2CF3at 70∘C




O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

O

O

NH

O

O

NH

O

O

N

+

Alloc

NH

ClCl

MeO79



Cl Cl

80MeO

81

MeO82

MeO


N

N

N

N

O

+

+

CH3 CH3

CH3

HO

8384

85

Au

H3C

CH2Cl2 rt 2h

(25mol)


BF minus4

77

86

AgBF4 (5mol)







AgBF4








O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

NH N

H

+

87 8889

NHR1 R2

R1 R2

AgBF4

refluxCH2Cl2


O

NH

NH

N

N N

NH

NH

NH

89

87

88

+Ag

R1

R1 R1R2

R1

R2R1R2R2

90 91

HO

minusH2O87

Indole

92

Ag+Ag+

∙∙

∙∙

R1


N

N

H

N

N

H

NH

N

NH

N

NH

N

93

CH3 CH3

CH3

CH3

CH3

CN

AgBF4

BF minus4

94

97

THF rt 3hAgBF4 THF

Et3N rt 3hPhO2S

PhO2S

95a

95b

H3CO2C

H3CO2C

CO2CH3

CO2CH3

96

NCNa+

+

minus

+

NC





O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

O

O

NH

O

O

NH

98 9987

100

BrBr

BrAgBF4 THF


N

N H

ClH N

N H

H

N

NVindoline

101

102

OTs

OTs

MeO

Me HO OAc

CO2CH3

CO2CH3

CO2CH3

C6H5

C6H5

AgBF4

OSiMe3

OSiMe3


O

OROR

O

+

104 105

AgBF4

103

(Bmim)BF4

R = alkyl aryl

N2











2 25mol


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


O

OR OR

OO

OR

R

O

R

O

O

Carbene106

Cyclopropaneformed

107

104

compoundDiazo

103

N2Ag(I)

Ringclosure

105Zwitterion

intermediate108

Bondcleavage

Ominus

+

minusN2

∙∙


HI O

IH

CH-TMSDIP

O

109110

111112

+PhSO2

SO2PhOSiMe3

AgBF4 Et3NCH2SO2Ph

CH2I


TsNR

TsN

R

F

(15 equiv)


113114

nBu

nBu

AgBF4

∘90 C 2h


AgBF4 30mol NCC








TsNR

ArX

R

TsN TsN

Ag

R

AgAg

R

TsNF

Ag

R

TsN

113Thermal

115

116

118

117119

nBu

nBu

nBunBu

nBu

H+

Ag+

+

+Fminus



2BrCl The resulting







HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


HO

11 equiv TMSOMe

Nitromethane120

121

122


30mol NCC6F5

11 equiv XeF2

0∘C

O

HF

O

H


O

BrF

O

Dry ether

123 124

R3

AgBF4

R3

R2R2

R1


R1 = R2ne H R3

ne Cl


Br

O

Nu

O

124

R1R1R1

R3

R3R3

R2

R2R2

125

minusAgBr

123

NuO+

Ag+

∙∙


PhSH

126127 128


AgBF4


130

132131

129R1R2CX2 + 2AgBF4

R1R2CX3 + 3AgBF4







4139 catalyst



C X

Ag

CX

F

C F

F

C X

C FF

CX

X

CF

F

133

R1

R2R2 R2

R2

R1 R1

R1 R1R1

R2 R2R2

R1

129

Ag

134BF3

BF3

minus

minus

+ + +

+

+

+

135

130 137 136


4

N

N

Cl

F

Ph

F

Ph

138

20 equiv

Ag(I) 20 equiv

139

140

BF minus4

BF minus4

acetone 90∘C 2h

Si(OEt)3





Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Te Te Te

RHet

H RHet


143

144

145

BF minus4

15 equiv

++

Me2SOTf2O



CF3

CF3CF3CF3TfOminus


RR

OAc

H

X

146 147

AgBF4

R = alkyl aryl



OH

OH

X


148 149

AgBF4 (5mol)


R2

R1

R1

R3 + NXS


I

Ph

Ph

Ph

OH

I

OH

PhH

151

Ph

OH

Ph

I

Ph

IO

Ph

H

HPh

I

OH

I

Ph OH

OH

150



Friedel-Crafts

Tautomerization

Elimination

152

153 154

155 156 149

cyclization

I+

I+

+

+

+

H+

+

OHminus

Ag+

minus






2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





2 and Cu(OAc)










2Cl2(10mL)


7 Conclusions


4-






Acknowledgment


References




































4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




















4-
















































4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





























4H+ reduction of





























































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

review article bioactive phytochemicals: bioactivity, sources,...

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