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A green and rapid approach for the stereoselective vinylation of phenol, thioland amine derivatives in water†

Yaghoub Sarrafi,* Marzieh Sadatshahabi, Kamal Alimohammadi and Mahmood Tajbakhsh

Received 30th May 2011, Accepted 20th July 2011DOI: 10.1039/c1gc15625j

The stereoselective formation of C–O, C–S and C–N bonds by the reaction of phenols, thiols andamines with activated alkynes is described. The reactions are successfully conducted in water withexcellent yields at room temperature. The lack of organic solvent use in the work-up procedure,the short reaction time and the environmentally benign mild reaction conditions are advantages ofthis method.

Introduction

A basic issue for sustainable growth in the chemical industryis the further development of green chemistry. The conceptof green chemistry has been adopted in organic synthesis tomeet the essential challenges of protecting human health andthe environment from chemical hazards.1 The most promisingway to attain this objective is undoubtedly to carry outreactions under aqueous conditions for economical and safetyreasons.2-4 Furthermore, using water as a solvent also offersmany advantages, such as simplicity of reaction conditions, easeof work-up and product isolation, increasing the selectivity ofa wide variety of organic reactions and accelerating reactionrates.2a,5 Recently, water has been employed as a solvent in manyorganic transformations, for example, in the formation of C–S,6

C–N7 and C–O8 bonds by conjugated addition reactions.The vinyl–nitrogen bond is a versatile functional group

capable of partaking in a variety of important reactions,including regioselective alkylation and acylation, annulationcascade and cycloaddition.9 Aryl vinyl ethers and sulfidesare employed as a key synthetic intermediates in the stere-oselective synthesis of substituted alkenes,10 the generationof natural product analogs,11 selective herbicides,12 new poly-meric materials13 and as valuable compounds found in manybiologically-active molecules.14 They are involved in reactionssuch as cycloadditions,15 hydroformylations,16 transition metal-catalyzed carbon–carbon bond formation,17 Michael acceptors18

and enolate equivalents.19

Over the years, several methods have been developed tosynthesize enamines, aryl vinyl ethers and sulfides, such as the

Department of Organic Chemistry, Faculty of Chemistry, University ofMazandaran, Babolsar, 47416, Islamic Republic of Iran.E-mail: ysarrafi@umz.ac.ir† Electronic supplementary information (ESI) available: Detailed exper-imental procedure, including 1H NMR and 13C NMR spectra for all newcompounds. See DOI: 10.1039/c1gc15625j

condensation of amines with b-dicarbonyl compounds,20 thedehydrohalogenation of aryl 2-haloethyl ethers,21 Michael-typeaddition–elimination processes,22 allyl ether isomerization,23

amine, phenols or thiol addition to acetylene derivatives underdifferent conditions,24–31 the coupling of vinyl halides withamines, phenols or thiols,32 the Wittig reaction33 and thecoupling of various vinyl sources with amines, phenols or thiolsin conjunction with a metal catalyst.34–37

Although all of these methods are effective, some of themhave drawbacks, such as harsh reaction conditions,26–28,32d longreaction times,24o,32e,34a,36,37 low yields,29,31 the use of expensivecatalysts,24a,32e,34a,36,37 tedious work-ups25 and the formation ofstereoisomer mixtures.20b,24a,i,l,29,30,32e Thus, there remains a needto develop an operationally simple, selective, mild and usefulmethod under green reaction conditions.

Results and discussion

As a part of our program aimed at developing new selectiveand environmentally friendly methodologies for the preparationof organic compounds,38 we report an efficient and green routefor the stereoselective formation of C–O, C–S and C–N bondsthrough the reaction of a wide range of substituted phenols,thiols and amines with dialkyl acetylenedicarboxylates in thepresence of potassium carbonate in water (Scheme 1).

Scheme 1 Reaction of phenols, thiols and amines with dialkylacetylenedicarboxylates in the presence of potassium carbonate in waterat room temperature.

This journal is © The Royal Society of Chemistry 2011 Green Chem., 2011, 13, 2851–2858 | 2851

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Table 1 Stereoselective synthesis of aryl vinyl ethers in water at roomtemperature

Entry R R¢ Product (Z) yield (%)

1 Phenyl Me 1a 98, 99a

2 4-Chlorophenyl Me 1b 973 4-Bromophenyl Me 1c 964 3-Nitrophenyl Me 1d 945 4-Nitrophenyl Me 1e 956 2,6-Dimethylphenyl Me 1f 917 2,5-Dimethylphenyl Me 1g 928 2,6-Dichlorophenyl Me 1h 909 3-Methoxyphenyl Me 1i 9310 1-Naphthyl Me 1j 8911 2-Naphthyl Me 1k 9212 Phenyl Et 1l 9013 2-Chlorophenyl Et 1m 8114 4-Bromophenyl Et 1n 8315 2,6-Dimethylphenyl Et 1o 7916 3-Methoxyphenyl Et 1p 8217 3-Nitrophenyl Et 1q 8518 2-Naphthyl Et 1r 8019 Phenyl t-Bu — No reaction20 2,4-Di-tert-butylphenyl Me — No reaction21 2-Formyl phenyl Me 1s 9622b 4-Bromo-2-formyl phenyl Me 1t 9423b 4-Chloro-2-formyl phenyl Me 1u 9324 2-Formyl phenyl Et 1v 8125b 4-Bromo-2-formyl phenyl Et 1w 8426b 4-Chloro-2-formyl phenyl Et 1x 83

a Phenol (100 mmol) was allowed to react with DMAD (100 mmol) inthe presence of K2CO3 in water at room temperature. b NaOH was usedinstead of K2CO3.

At the beginning of the present study, we conducted the reac-tion of phenol derivatives with dimethyl acetylenedicarboxylate(DMAD) in an aqueous solution of K2CO3 (Table 1, entries1–11). The reactions were rapid and stereoselectively affordedthe corresponding fumarate aryl vinyl ethers in excellent yieldsafter only 5–15 min at room temperature. After completion ofthe reaction, the crude product was simply collected from theaqueous medium by filtration or decantation. The structures ofthe products were assigned using spectroscopic data, and their1H NMR spectra clearly indicated the formation of the fumaratestereoisomer as the sole product based on the vinylic protonpositions in comparison with previously reported values.27,30,31,39

As shown in Table 1, when phenolic substrates with electron-withdrawing or electron-donating groups were used, the reactiontime and yields were not affected.

To evaluate the scope of this transformation, the reactionof bulky acetylenic esters or phenols containing a bulkygroup on the ortho position was investigated. When diethylacetylenedicarboxylate (DEAD) was subjected to the reactionconditions, slightly lower yields of aryl vinyl ethers were obtained(Table 1, entries 12–18). However, in the case of di(tert-butyl)acetylenedicarboxylate or 2,4-di-tert-butylphenol, which are notsoluble in aqueous media, the reaction did not occur, even aftera long reaction time and a higher temperature (Table 1, entries19 and 20). Upon repeating the reactions of entries 19 and 20in acetone/water (1 : 1) to dissolve the starting materials, onlythe reaction of entry 19 proceeded to give a mixture of E,Z arylvinyl ethers (10 : 90). The lack of formation of product in entry20 could be due to the steric effect of 2,4-di-tert-butylphenol.

More interesting results were obtained when salicylaldehydederivatives were reacted with acetylenedicarboxylate esters un-der the same reaction conditions (Scheme 2). Salicylaldehyde ina reaction with DMAD gave exclusively the (Z)-configurationof O-vinylic salicylaldehyde in high yield. However, when thisreaction was carried out in aprotic solvents such as acetonitrileor acetone, a mixture of E,Z-isomers of vinyl ether 1 and 4H-chromen 3 was obtained.

Scheme 2 Selective synthesis of O-vinylic salicylaldehydes.

Similarly, chloro and bromo salicylaldehydes afforded (Z)-vinyl ethers selectively in excellent yields without the formationof any (E)-isomer and 4H-chromen (Table 1, entries 21–26).To the best of our knowledge, this selectivity has not beenobserved before, as all the previously reported procedures gave4H-chromen and E,Z-isomers of the expected vinyl ethers.40

In order to demonstrate the importance of water as a moresuperior solvent than organic solvents, a few further experimentswere performed. Salicylaldehyde was treated with DMADin MeOH in the presence of K2CO3 at room temperature.Dimethyl-2-methoxy-butendioate from the attack of methanolat DMAD as the main product, and a trace amount of thecorresponding vinyl ether and 4H-chromen 3 were formed.When this reaction was carried out in MeOH/H2O (1 : 1), thearyl vinyl ether as the major product together with a smallamount of dimethyl-2-methoxy-butendioate and 4H-chromen3 were obtained. According to these observations, togetherwith the results obtained in the aprotic solvents mentionedpreviously, a possible explanation could be the insolubilityand fast protonation of the carbanion intermediate in water,which reduces significantly the chance of isomerization and self-condensation to form compound 3.

Due to the importance of divinyl ethers as interesting pre-cursors in polymer chemistry, as components of homo- andcopolymers, the reactions of dihydroxybenzenes were investi-gated. Hydroquinone and resorcinol were reacted with 2 mol ofDMAD or DEAD to afford the expected bis(vinyloxy)benzenederivatives under optimal conditions (Table 2, entries 1–4).However, as indicated in Table 2, in the case of pyrocatechol,only a trace amount of the corresponding adduct was obtained(Table 2, entries 5 and 6).

To extend the generality and applicability of this method,C–S and C–N bond formation via the coupling of mercaptansand amines with dialkyl acetylenedicarboxylates was examined.Various aliphatic and aromatic thiols, and secondary aminesgenerated the desired products under the optimal reactionconditions in higher yield and purity (Table 3).

2852 | Green Chem., 2011, 13, 2851–2858 This journal is © The Royal Society of Chemistry 2011

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Table 2 Stereoselective synthesis of bis(vinyloxy)benzenes in water atroom temperature

Entry Substrate R¢ Product (Z) yield (%)

1 Hydroquinone Me 4a 952 Resorcinol Me 4b 923 Hydroquinone Et 4c 874 Resorcinol Et 4d 795 Pyrocatechol Me 4e 66 Pyrocatechol Et — Trace

Table 3 Stereoselective synthesis of aryl vinyl sulfides and enamines inwater at room temperature

Entry Substrate R¢ Product (Z) yield (%)

1 Thiophenol Me 2a 972 4-Methyl thiophenol Me 2b 963 2-Naphthylthiol Me 2c 934 Cyclohexylthiol Me 2d 975 Pentylthiol Me 2e 946 Thiophenol Et 2f 897 4-Bromo thiophenol Et 2g 878 4-Methyl thiophenol Et 2h 849 Cyclohexylthiol Et 2i 8510 Piperidine Me 2j 9711 N-Methylaniline Me 2k 9712 Morpholine Me 2l 9613 Piperidine Et 2m 9014 N-Methylaniline Et 2n 8715 Morpholine Et 2o 89

Table 4 Reactions of various nucleophiles with methyl- and ethyl-propiolate

Entry Substrate R¢ Product (Z) yield (%)

1 Phenol Me 5a 932 4-Chlorophenol Me 5b 923 2-Formyl phenol Me 5c 894 Thiophenol Me 5d 945 Cyclohexylthiol Me 5e 926 Piperidine Me 5f 957 Phenol Et 5g 898 Thiophenol Et 5h 869 Cyclohexylthiol Et 5i 8310 Piperidine Et 5j 83

The reaction of dialkyl acetylenedicarboxylates with primaryamines did not give satisfactory results.

Furthermore, to expand the reaction scope, other activatedalkynes, such as methyl- and ethyl-propiolate, were treated withphenols, thiols and amines (Table 4). It was found that excellent

stereoselectivity was obtained under the same conditions. Allthe reactions proceeded rapidly (within 10–15 min) to give onlythe (Z)-form conjugate addition product. The results of usingthis mild and simple procedure are shown in Table 4. The 1HNMR spectra of the products displayed two doublets with acoupling constant corresponding to the (Z)-form isomer for thetwo olefinic protons, which is in agreement with values reportedin the literature.32j,41

In order to demonstrate the applicability of this method, alarge-scale experiment was run. The reaction of 100 mmol (9.4 g)phenol with DMAD under the same reaction conditions gave1a in almost the same yield as on the small scale (99%, Table 1,entry 1).

Conclusions

In summary, we have developed a stereoselective, mild, single-step and green procedure for the preparation of aryl vinyl ethers,aryl vinyl sulfides and enamines through the direct coupling ofvarious substituted phenols, thiols and amines with activatedalkynes in water at room temperature. This process leadsexclusively to the (Z)-configuration of the vinylation products.The availability of the starting material, short reaction times,quantitative yields of products and the fairly mild reactionconditions without using any volatile organic solvents make thisprotocol convenient for industrial applications.

Experimental

General considerations

Melting points were measured on an Electrothermal 9100apparatus. Infrared spectra were recorded on a Shimadzu IR-8300 series FT-IR spectrophotometer. 1H NMR and 13C NMRspectra were recorded on a Bruker 400-MHz instrument inCDCl3 solvent with TMS as a standard. Mass spectra wererecorded by a Jeol DX303 HF mass spectrometer. Elementalanalyses were carried out using a Perkin-Elmer CHN 2400instrument.

Typical procedure for the synthesis of 1a

Phenol (0.188 g, 2 mmol) was dissolved in aqueous solutionof K2CO3 (0.276 g, 2 mmol) and DMAD (0.284 g, 2 mmol)was added. The reaction mixture was stirred vigorously atroom temperature. A turbid solution was formed which byconsumption of phenol (monitored by TLC) in 5 min, thereaction mixture became clear and dimethyl (Z)-2-(phenoxy)-2-butenedioate 1a existed as solid in water. The product wasisolated by filtration without further purification.

Compounds 1a–f, 1j, 1k, 1s, 1v, 1w and 5h are knowncompounds, and were characterized by comparison oftheir physical and spectroscopic data with those previouslyreported.24n,o,27,30,31,32j,40 The physical properties and spectral dataof the new compounds are reported here.

Dimethyl (Z)-2-(2,5-dimethylphenoxy)-2-butenedioate (1g).White solid. mp 53–55 ◦C. 1H NMR (400 MHz, CDCl3): d2.26 (s, 3H, CH3), 2.33 (s, 3H, CH3), 3.73 (s, 3H, OCH3), 3.75(s, 3H, OCH3), 6.50 (s, 1H, Ar–H), 6.55 (s, 1H, HC C), 6.80

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(d, 1H, J = 7.6 Hz, Ar–H), 7.08 (d, 1H, J = 7.6 Hz, Ar–H). 13CNMR (100 MHz, CDCl3): d 15.68, 21.02 (2CH3), 51.88, 52.97(2OCH3), 113.81, 115.09, 124.19, 124.68, 131.00, 136.61, 150.62,154.75 (4CH, 4C), 162.79, 164.13 (2C O, ester). IR (KBr, nmax,cm-1): 1732, 1634, 1425, 1210. Elemental analysis for C14H16O5:Calc. C, 63.63; H, 6.10. Found: C, 63.75; H, 6.23. EIMS: m/z264.1 (M+).

Dimethyl (Z)-2-(2,6-dichlorophenoxy)-2-butenedioate (1h).White solid. mp 40–42 ◦C. 1H NMR (400 MHz, CDCl3): d 3.72(s, 3H, OCH3), 3.77 (s, 3H, OCH3), 6.68 (s, 1H, HC C), 6.76 (d,1H, J = 8.8 Hz, Ar–H), 7.14 (dd, 1H, J = 7.6 Hz, J = 2.4 Hz, Ar–H), 7.42 (d, 1H, J = 2.4 Hz, Ar–H). 13C NMR (100 MHz, CDCl3):d 52.15, 53.27 (2OCH3), 115.89, 116.94, 124.40, 127.61, 128.77,130.45, 149.01, 151.20 (4C, 4CH), 161.80, 163.40 (2C O, ester).IR (KBr, nmax, cm-1): 1724, 1655, 1487, 1212, 1100. Elementalanalysis for C14H16O5: Calc. C, 47.24; H, 3.30. Found: C, 47.12;H, 3.44. EIMS: m/z 303.8 (M+).

Dimethyl (Z)-2-(3-Methoxyphenoxy)-2-butenedioate (1i).White solid. mp 56–57 ◦C. 1H NMR (400 MHz, CDCl3): d 3.73(s, 3H, OCH3), 3.77 (s, 3H, OCH3), 3.80 (s, 3H, OCH3), 6.61 (s,1H, HC C), 6.50–7.22 (m, 4H, Ar–H). 13C NMR (100 MHz,CDCl3): d 52.03, 53.06, 55.37 (3CH3), 102.49, 107.94, 109.21,115.16, 130.04 (5CH), 149.68, 157.61, 160.87 (3C), 162.64,163.85 (2C O, ester). IR (KBr, nmax, cm-1): 1747, 1645, 1460,1223, 1155. Elemental analysis for C13H14O6: Calc. C, 58.64; H,5.30. Found: C, 58.73; H, 5.19. EIMS: m/z 266 (M+).

Diethyl (Z)-2-(phenoxy)-2-butenedioate (1l). Yellow oil. 1HNMR (400 MHz, CDCl3): d 0.91 (t, 3H, J = 7.2 Hz, CH3), 1.33 (t,3H, J = 7.2 Hz, CH3), 3.81 (q, 2H, J = 7.2 Hz, OCH2), 4.27 (q, 2H,J = 7.2 Hz, OCH2), 6.40 (s, 1H, HC C), 6.31–7.48 (m, 5H, Ar–H). 13C NMR (100 MHz, CDCl3): d 13.50, 14.26 (2CH3), 60.95,62.20 (2CH2), 119.46 ( CH), 128.81, 129.04, 132.35, 133.22(CH, C-Ar), 149.46 ( C), 164.48, 165.19 (2C O, ester). IR(neat, nmax, cm-1): 1737, 1654, 1221, 1196. Elemental analysisfor C14H16O5: Calc. C, 63.63; H, 6.10. Found: C, 63.75; H, 6.29.EIMS: m/z 264.1 (M+).

Diethyl (Z)-2-(2-chlorophenoxy)-2-butenedioate (1m). Yel-low oil. 1H NMR (400 MHz, CDCl3): d 1.17 (t, 3H, J = 7.2 Hz,CH3), 1.20 (t, 3H, J = 7.2 Hz, CH3), 4.17 (q, 2H, J = 7.2 Hz,OCH2), 4.19 (q, 2H, J = 7.2 Hz, OCH2), 6.65 (s, 1H, HC C),6.82–7.42 (m, 4H, Ar–H). 13C NMR (100 MHz, CDCl3): d13.79, 13.94 (2CH3), 61.07, 62.40 (2CH2), 115.64, 116.20, 123.48,124.09, 127.52, 130.65, 149.46, 152.47 (5CH, 3C), 161.46, 163.28(2C O, ester). IR (neat, nmax, cm-1): 1750, 1634, 1454, 1211,1186. Elemental analysis for C14H15ClO5: Calc. C, 56.29; H, 5.06.Found: C, 56.36; H, 4.95. EIMS: m/z 297.9 (M+).

Diethyl (Z)-2-(4-bromophenoxy)-2-butenedioate (1n). Yel-low oil. 1H NMR (400 MHz, CDCl3): d 1.41 (2t, 6H, J = 7.2,2CH3), 4.17 (q, 2H, J = 7.2 Hz, OCH2), 4.20 (q, 2H, J = 7.2 Hz,CH2), 6.83 (s, 1H, HC C), 6.85 (d, 2H, J = 8.8 Hz, Ar–H),7.39 (d, 2H, J = 8.8 Hz, Ar–H). 13C NMR (100 MHz, CDCl3): d13.89, 14.02 (2CH3), 61.09, 62.44 (2CH2), 115.80, 116.00, 117.93,132.48, 149.42, 155.83 (CH, C), 161.81, 163.34 (2C O, ester).IR (neat, nmax, cm-1): 1744, 1619, 1222, 1169. Elemental analysisfor C14H15BrO5: Calc. C, 56.29; H, 5.06. Found: C, 56.36; H,4.90. EIMS: m/z 342 (M+).

Diethyl (Z)-2-(2,6-dimethylphenoxy)-2-butenedioate (1o).Yellow oil. 1H NMR (400 MHz, CDCl3): d 1.16 (t, 3H, J =7.2 Hz, CH3), 1.24 (t, 3H, J = 7.2 Hz, CH3), 2.26 (s, 3H, CH3),2.28 (s, 3H, CH3), 4.05 (q, 2H, J = 7.2 Hz, OCH2), 4.16 (q, 2H,J = 7.2 Hz, OCH2), 6.08 (s, 1H, HC C), 6.95–7.01 (m, 3H,Ar–H). 13C NMR (100 MHz, CDCl3): d 13.76, 14.07, 15.89,16.89 (4CH3), 60.61, 62.16 (2CH2), 105.35, 120.14, 124.99,128.58, 129.90, 151.79, 152.42 (4C, 4CH), 162.258, 164.18(2C O, ester). IR (neat, nmax, cm-1): 1727, 1662, 1205, 1131.Elemental analysis for C16H20O5: Calc. C, 65.74; H, 6.90.Found: C, 65.60; H, 6.95. EIMS: m/z 292.1 (M+).

Diethyl (Z)-2-(3-methoxyphenoxy)-2-butenedioate (1p). Yel-low oil. 1H NMR (400 MHz, CDCl3): d 1.19 (t, 3H, J = 7.2 Hz,CH3), 1.23 (t, 3H, J = 7.2 Hz, CH3), 3.77 (s, 3H, OCH3), 4.19(2q, 4H, J = 7.2 Hz, 2OCH2), 6.58 (s, 1H, HC C), 6.51–7.20 (m, 4H, Ar–H). 13C NMR (100 MHz, CDCl3): d 13.87,14.03, 55.35 (3CH3), 60.99, 62.29 (2CH2), 102.53, 108.09, 109.16,115.18, 129.95 (5CH), 149.90, 157.72, 160.82 (3C), 162.18,163.57 (2C O, ester). IR (neat, nmax, cm-1): 1738, 1636, 1220,1145. Elemental analysis for C15H18O6: Calc. C, 61.22; H, 6.16.Found: C, 61.13; H, 6.04. EIMS: m/z 294.1 (M+).

Diethyl (Z)-2-(3-nitrophenoxy)-2-butenedioate (1q). Yellowoil. 1H NMR (400 MHz, CDCl3): d 1.21 (t, 3H, J = 7.2 Hz, CH3),1.25 (t, 3H, J = 7.2 Hz, CH3), 4.18 (q, 2H, J = 7.2 Hz, OCH2),4.26 (q, 2H, J = 7.2 Hz, OCH2), 6.80 (s, 1H, HC C), 7.056 (d,2H, J = 9.2 Hz, Ar–H); 8.24 (d, 2H, J = 9.2 Hz, Ar–H). 13CNMR (100 MHz, CDCl3): d 13.95, 13.99 (2CH3), 61.36, 62.82(2CH2), 116.03, 117.83, 120.27, 125.89, 148.33, 161.24 (5CH,3C), 161.50, 162.82 (2C O, ester). IR (neat, nmax, cm-1): 1758,1640, 1217, 1155. Elemental analysis for C14H15NO7: Calc. C,54.37; H, 4.89. Found: C, 54.25; H, 4.97. EIMS: m/z 309 (M+).

Diethyl (Z)-2-(2-naphtoxy)-2-butenedioate (1r). Yellow oil.1H NMR (400 MHz, CDCl3): d 1.15 (t, 3H, J = 7.2 Hz, CH3),1.22 (t, 3H, J = 7.2 Hz, CH3), 4.19 (q, 4H, J = 7.2 Hz, 2OCH2),6.70 (s, 1H, HC C), 7.23–7.85 (m, 6H, Ar–H). 13C NMR(100 MHz, CDCl3): d 13.87, 14.05 (2CH3), 61.00, 62.32 (2CH2),110.88, 115.58, 118.09, 124.72, 126.65, 127.11, 127.80, 129.91,130.65 (5CH), 130.18, 133.99, 150.02, 154.64 (4C), 162.23,163.57 (2C O, ester). IR (neat, nmax, cm-1): 1734, 1668, 1265,1158. Elemental analysis for C18H18O5: Calc. C, 68.78; H, 5.77.Found: C, 68.70; H, 5.64. EIMS: m/z 314.1 (M+).

Dimethyl 2-(4-bromo-2-formylphenoxy)-2-butenedioate (1t).White solid. mp 88–90 ◦C. 1H NMR (400 MHz, CDCl3): d 3.74,3.81 (2 s, 6H, 2OCH3), 6.76 (d, 1H, J = 8 Hz, Ar–H), 6.79 (s,1H, HC C), 7.59 (dd, 1H, J = 8 Hz, J = 4 Hz, Ar–H), 8.02 (d,1H, J = 4 Hz, Ar–H), 10.47 (s, 1H, CHO). 13C NMR (100 MHz,CDCl3): d 52.31, 53.43 (2CH3), 116.79, 117.32, 117.35, 131.25,137.96, 148.66, 157.78 (CH, C), 161.80, 163.22 (2C O, ester),187.56 (CHO). IR (KBr, nmax, cm-1): 2830, 1747, 1720, 1646,1200, 1141. Elemental analysis for C13H11BrO6: Calc. C, 45.50;H, 3.23. Found: C, 45.65; H, 3.31. EIMS: m/z 341.9 (M+).

Dimethyl 2-(4-chloro-2-formylphenoxy)-2-butenedioate (1u).White solid. mp 96–98 ◦C. 1H NMR (400 MHz, CDCl3): d 3.75,3.80 (2 s, 6H, 2OCH3), 6.79 (s, 1H, HC C), 6.82 (d, J = 8.8 Hz,1H, Ar–H), 7.45 (dd, J = 8.8 Hz, J = 2.6 Hz, 1H, Ar–H), 7.88 (d,J = 2.8 Hz, 1H, Ar–H), 10.48 (s, 1H, CHO). 13C NMR (100 MHz,

2854 | Green Chem., 2011, 13, 2851–2858 This journal is © The Royal Society of Chemistry 2011

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CDCl3): d 52.30, 53.42 (2CH3), 117.00, 117.27, 128.22, 126.64,135.06, 129.56, 148.75, 157.26 (C, CH), 161.84, 163.24 (2C O,ester), 187.68 (CHO). IR (KBr, nmax, cm-1): 2843, 1740, 1723,1627, 1211, 1189. Elemental analysis for C13H11ClO6: Calc. C,52.28; H, 3.71. Found: C, 52.37; H, 3.62. EIMS: m/z 298 (M+).

Diethyl 2-(4-chloro-2-formylphenoxy)-2-butenedioate (1x).Yellow oil. 1H NMR (400 MHz, CDCl3): d 1.238 (2t, 6H, J =7.2 Hz, 2CH3), 4.21 (q, 2H, J = 7.2 Hz, OCH2), 4.24 (q, 2H,J = 7.2 Hz, OCH2), 6.78 (s, 1H, HC C), 6.84 (d, 1H, J =8.8 Hz, Ar–H), 7.46 (dd, 1H, J = 8.8 Hz, 2.8 Hz, Ar–H), 8.88(d, 1H, J = 2.8 Hz, Ar–H), 10.50 (s, 1H, CHO). 13C NMR(100 MHz, CDCl3): d 13.92, 14.02 (2CH3), 61.38, 62.80 (2CH2),117.11 ( CH), 117.55, 126.64, 128.10, 129.45, 135.01, 157.39(C, CH-Ar), 148.77 ( C), 161.36, 162.91 (2C O, ester), 187.75(CHO). IR (neat, nmax, cm-1): 2891, 1741, 1719, 1639, 1205,1176. Elemental analysis for C15H15ClO6: Calc. C, 55.14; H, 4.63.Found: C, 55.01; H, 4.50. EIMS: m/z 326 (M+).

Dimethyl (Z)-2-(phenylthio)-2-butenedioate (2a). Yellow oil.1H NMR (400 MHz, CDCl3): d 3.33 (s, 3H, OCH3), 3.79 (s, 3H,OCH3), 6.37 (s, 1H, HC C), 7.28–7.48 (5H, Ar–H). 13C NMR(100 MHz, CDCl3): d 51.89, 52.60 (2CH3), 118.69 ( CH),128.95, 130.51, 133.35, 134.28 (C, CH-Ar), 149.94 ( C), 164.78,165.53 (2C O, ester). IR (neat, nmax, cm-1): 1745, 1617, 1474,1229. Elemental analysis for C12H12O4S: Calc. C, 57.13; H, 4.79.Found: C, 57.26; H, 4.65. EIMS: m/z 252 (M+).

Dimethyl (Z)-2-(4-methylphenylthio)-2-butenedioate (2b).Yellow solid. mp 77–79 ◦C. 1H NMR (400 MHz, CDCl3): d2.33 (s, 3H, CH3), 3.34 (s, 3H, OCH3), 3.78 (s, 3H, OCH3),6.29 (s, 1H, HC C), 7.13 (d, 2H, J = 7.6, Ar–H), 7.36 (d, 2H,J = 8, Ar–H). 13C NMR (100 MHz, CDCl3): d 21.20, 51.86,52.54 (3CH3), 117.67 (CH), 128.14, 129.80, 133.64, 139.30 (C,CH-Ar), 150.79 (C), 164.82, 165.59 (2C O, ester). IR (KBr,nmax, cm-1): 1720, 1654, 1585, 1425, 1190. Elemental analysis forC13H14O4S: Calc. C, 58.63; H, 5.30. Found: C, 58.51; H, 5.23.EIMS: m/z 266 (M+).

Dimethyl (Z)-2-(naphtylthio)-2-butenedioate (2c). Pale yel-low solid. mp 60–62 ◦C. 1H NMR (400 MHz, CDCl3): d 3.28,3.84 (s, 6H, 2OCH3), 6.47 (s, 1H, HC C), 7.48–7.99 (m, 7H, Ar–H). 13C NMR (100 MHz, CDCl3): d 52.00, 52.69 (2CH3), 119.41( CH), 126.86, 127.07, 128.72, 129.37, 29.73, 132.77, 132.91,133.37 (C, CH-Ar), 149.58 ( C), 164.85, 165.57 (2C O, ester).IR (KBr, nmax, cm-1): 1724, 1650, 1585, 1195. Elemental analysisfor C16H14O4S: Calc. C, 63.56; H, 4.67. Found: C, 63.45; H, 6.75.EIMS: m/z 302 (M+).

Dimethyl (Z)-2-(cyclohexylthio)-2-butenedioate (2d). Yellowoil. 1H NMR (400 MHz, CDCl3): d 1.34–1.90 (10H, 5CH2,cyclohexan), 3.27 (tt, 1H, J = 10.6 Hz, J = 3.6 Hz, CH-Cyclohexan), 3.76 (s, 3H, OCH3), 3.86 (s, 3H, OCH3), 6.38 (s, 1H,HC C). 13C NMR (100 MHz, CDCl3): d 25.34, 25.93 (2CH3),33.80, 44.95, 51.73, 53.06 (CH, CH2), 120.26 ( CH), 148.04( C), 165.30, 165.55 (2C O, ester). IR (neat, nmax, cm-1): 1740,1623, 1474, 1210. Elemental analysis for C12H18O4S: Calc. C,55.79; H, 7.02. Found: C, 55.88; H, 6.91. EIMS: m/z 258 (M+).

Dimethyl (Z)-2-(pentylthio)-2-butenedioate (2e). Yellow oil.1H NMR (400 MHz, CDCl3): d 0.87 (t, 3H, J = 7.0, CH3), 1.35(m, 2H, CH2), 1.57 (m, 2H, CH2), 2.81 (t, 2H, J = 7.4, CH2–S),

3.74 (s, 3H, OCH3), 3.84 (s, 3H, OCH3), 6.30 (s, 1H, HC C). 13CNMR (100 MHz, CDCl3): d 13.83 (CH3), 22.10, 29.31, 30.79,32.57 (4CH2), 51.68, 52.97 (2OCH3), 118.57 ( CH), 149.53( C), 164.94, 165.62 (2C O, ester). IR (neat, nmax, cm-1): 1755,1474, 1229, 1117. Elemental analysis for C11H18O4S: Calc. C,53.64; H, 7.37. Found: C, 53.60; H, 7.49. EIMS: m/z 246 (M+).

Diethyl (Z)-2-(phenylthio)-2-butenedioate (2f). Yellow oil.1H NMR (400 MHz, CDCl3): d 0.91 (t, 3H, J = 7.2 Hz, CH3),1.33 (t, 3H, J = 7.2 Hz, CH3), 3.81 (q, 2H, J = 7.2 Hz, OCH2), 4.27(q, 2H, J = 7.2 Hz, OCH2), 6.40 (s, 1H, HC C), 7.32–7.48 (m,5H, Ar–H). 13C NMR (100 MHz, CDCl3): d 13.50, 14.26 (2CH3),60.95, 62.20 (2OCH2), 119.46 ( CH), 128.81, 129.04, 132.35,133.22 (CH, C-Ar), 149.59 ( C), 164.48, 165.19 (2C O, ester).IR (neat, nmax, cm-1): 1731, 1429, 1198, 1123. Elemental analysisfor C14H16O4S: Calc. C, 59.98; H, 5.75. Found: C, 59.89; H, 5.65.EIMS: m/z 280 (M+).

Diethyl (Z)-2-(4-bromophenylthio)-2-butenedioate (2g). Yel-low solid. mp 64–65 ◦C. 1H NMR (400 MHz, CDCl3): d 0.98 (t,3H, J = 7.2 Hz, CH3), 1.33 (t, 3H, J = 7.2 Hz, CH3), 3.88 (q, 2H,J = 7.2 Hz, OCH2), 4.26 (q, 2H, J = 7.2 Hz, OCH2), 6.45 (s, 1H,HC C), 7.32 (d, 2H, J = 8.4 Hz, Ar–H), 7.46 (d, 2H, J = 8.8 Hz,Ar–H). 13C NMR (100 MHz, CDCl3): d 13.62, 14.24 (2CH3),61.10, 62.38 (2OCH2), 120.72 ( CH), 123.24, 131.63 (C-Ar),132.18, 134.56 (4CH), 148.20 ( C), 164.14, 165.06 (2C O,ester). IR (KBr, nmax, cm-1): 1741, 1475, 1192, 1115. Elementalanalysis for C14H15BrO4S: Calc. C, 46.81; H, 4.21. Found: C,46.93; H, 4.30. EIMS: m/z 357.9 (M+).

Diethyl (Z)-2-(4-methylphenylthio)-2-butenedioate (2h). Yel-low oil. 1H NMR (400 MHz, CDCl3): d 0.94 (t, 3H, J = 7.2 Hz,CH3), 1.33 (t, 3H, J = 7.2 Hz, CH3), 2.34 (s, 3H, CH3), 3.81 (q,2H, J = 7.2 Hz, OCH2), 4.26 (q, 2H, J = 7.2 Hz, OCH2), 6.32 (s,1H, HC C), 7.13 (d, 2H, J = 8.4 Hz, Ar–H), 7.35 (d, 2H, J =8.4 Hz, Ar–H). 13C NMR (100 MHz, CDCl3): d 13.54, 14.26,21.20 (3CH3), 60.86, 62.11 (2OCH2), 118.38 ( CH), 129.75,129.04, 133.55, 128.45, 39.17 (CH, C-Ar), 150.48 ( C), 164.50,165.25 (2C O, ester). IR (neat, nmax, cm-1): 1752, 1646, 1220,1160. Elemental analysis for C15H18O4S: Calc. C, 61.20; H, 6.16.Found: C, 61.11; H, 6.08. EIMS: m/z 294 (M+).

Diethyl (Z)-2-(cyclohexylthio)-2-butenedioate (2i). Yellowoil. 1H NMR (400 MHz, CDCl3) d 1.36 (t, 3H, J = 7.2 Hz, CH3),1.38 (t, 3H, J = 7.2 Hz, CH3), 1.38–2.06 (10H, CH2 cyclohexan),3.31 (tt, 1H, J = 10.6 Hz, J = 3.6 Hz, CH-Cyclohexan), 4.22(q, 2H, J = 7.2 Hz, OCH2), 4.32 (q, 2H, J = 7.2 Hz, OCH2),6.35 (s, 1H, HC C). 13C NMR (100 MHz, CDCl3): d 14.13,14.17 (2CH3), 25.33, 25.94, 32.76, 44.65 (CH, CH2), 60.65,62.37 (2OCH3), 120.24 ( CH), 148.27 ( C), 164.83, 165.21(2C O, ester). IR (neat, nmax, cm-1): 1739, 1661, 1428, 1219,1153. Elemental analysis for C14H22O4S: Calc. C, 58.71; H, 7.74.Found: C, 58.59; H, 7.68. EIMS: m/z 286.1 (M+).

Dimethyl-(Z)-2-(piperidine-1-yl)-2-butenedioate (2j). Paleorange solid. mp 79–81 ◦C. 1H NMR (400 MHz, CDCl3): d1.62 (m, 6H, 3CH2), 3.15 (m, 4H, 2NCH2), 3.62 (s, 3H, OCH3),3.90 (s, 3H, OCH3), 4.72 (s, 1H, HC C). 13C NMR (100 MHz,CDCl3): d 23.91, 25.08, 48.57 (6CH2), 50.76, 52.78 (2CH3),84.68 ( CH), 154.55 ( C), 166.35, 168.39 (2C O, ester). IR(KBr, nmax, cm-1): 1736, 1445, 1173, 1152. Elemental analysis for

This journal is © The Royal Society of Chemistry 2011 Green Chem., 2011, 13, 2851–2858 | 2855

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C11H17NO4: Calc. C, 58.14; H, 7.54; N, 6.16. Found: C, 58.10;H, 7.60; N, 6.18. EIMS: m/z 227.1 (M+).

Dimethyl-(Z)-2-(phenylmethylamino)-2-butenedioate (2k).White solid. mp 72–73 ◦C. 1H NMR (400 MHz, CDCl3): d 3.24(s, 3H, CH3), 3.66 (s, 3H, OCH3), 3.69 (s, 3H, OCH3), 4.82 (s,1H, HC C), 7.20–7.40 (m, 5H, Ar–H). 13C NMR (100 MHz,CDCl3): d 40.83, 50.96, 52.63 (3CH3), 88.14 ( CH), 126.54,127.40, 129.46 (5CH-Ar), 144.55, 154.20 (2C), 165.34, 167.85(2C O, ester). IR (KBr, nmax, cm-1): 1749, 1434, 1218, 1118.Elemental analysis for C13H15NO4: Calc. C, 62.64; H, 6.07; N,5.62. Found: C, 62.72; H, 6.15; N, 5.71. EIMS: m/z 249.1 (M+).

Dimethyl-(Z)-2-(morpholino)-2-butenedioate (2l). Pale yel-low solid. mp 50–52 ◦C. 1H NMR (400 MHz, CDCl3): d 3.12(t, 4H, J = 4.8 Hz, 2NCH2), 3.63 (s, 3H, OCH3),. 3.72 (t,4H, J = 4.8 Hz, 2OCH2), 3.90 (s, 3H, OCH3), 4.78 (s, 1H,HC C). 13C NMR (100 MHz, CDCl3): d, 47.09, 51.02, 53.03,65.84 (CH2, CH3), 87.13 ( CH), 154.69 ( C), 165.83, 167.83(2C O, ester). IR (KBr, nmax, cm-1):1745, 1454, 1200, 1146.Elemental analysis for C10H15NO5: Calc. C, 52.40; H, 6.60; N,6.11. Found: C, 52.5; H, 6.73; N, 6.16. EIMS: m/z 229.1 (M+).

Diethyl-(Z)-2-(piperidine-1-yl)-2-butenedioate (2m). Yellowoil. 1H NMR (400 MHz, CDCl3): d 1.23 (t, 3H, J = 7.2 Hz,CH3), 1.37 (t, 3H, J = 7.2 Hz, CH3), 1.62 (m, 6H, 3CH2),3.17 (m, 4H, 2NCH2), 4.09 (q, 2H, J = 7.2 Hz, OCH2), 4.39(q, 2H, J = 7.2 Hz, OCH2), 4.73 (s, 1H, HC C). 13C NMR(100 MHz, CDCl3): d 13.93, 14.48 (2CH3), 23.98, 25.08, 48.52(5CH2), 59.21, 62.02 (2OCH2), 85.18 ( CH), 154.56 ( C),165.89, 167.82 (2C O, ester). IR (neat, nmax, cm-1): 1734, 1521,1444, 1152, 1129. Elemental analysis for C13H21NO4: Calc. C,61.16; H, 8.29; N, 5.49. Found: C, 61.21; H, 8.40; N, 5.58. EIMS:m/z 255.1 (M+).

Diethyl-(Z)-2-(phenylmethylamino)-2-butenedioate (2n).White solid. mp 66–68 ◦C. 1H NMR (400 MHz, CDCl3): d1.09 (t, 3H, J = 7.2 Hz, CH3), 1.24 (t, 3H, J = 7.2 Hz, CH3),3.23 (s, 3H, CH3), 4.01 (2q, 4H, J = 7.2 Hz, 2OCH2), 4.81 (s,1H, HC C), 7.21–7.38 (m, 5H, Ar–H). 13C NMR (100 MHz,CDCl3): d 13.62, 14.39, 40.83 (3CH3), 59.47, 61.75 (2OCH2),88.50 ( CH), 126.82, 127.38, 129.36 (5CH-Ar), 144.65, 154.16(2C), 164.75, 167.31 (2C O, ester). IR (KBr, nmax, cm-1): 1740,1453, 1201, 1171. Elemental analysis for C15H19NO4: Calc. C,64.07; H, 6.91; N, 5.05. Found: C, 64.00; H, 6.83; N, 5.11.EIMS: m/z 277.1 (M+).

Diethyl-(Z)-2-(morpholino)-2-butenedioate (2o). Yellow oil.1H NMR (400 MHz, CDCl3): d 1.21 (t, 3H, J = 7.2 Hz, CH3),1.35 (t, 3H, J = 7.2 Hz, CH3), 3.12 (t, 4H, J = 4.8 Hz, 2NCH2),3.72 (t, 4H, J = 4.8 Hz, 2OCH2), 4.09 (q, 2H, J = 7.2 Hz,CH2), 4.36 (q, 2H, J = 7.2 Hz, CH2), 4.77 (s, 1H, HC C). 13CNMR (100 MHz, CDCl3): d 13.90, 14.39 (2CH3), 47.04, 59.52,62.23, 65.86 (4CH2), 87.67 ( CH), 154.69 ( C), 165.36, 167.21(2C O, ester). IR (neat, nmax, cm-1): 1738, 1445, 1155, 1163.Elemental analysis for C12H16NO5: Calc. C, 56.02; H, 7.44; N,5.44. Found: C, 56.14; H, 7.5; N, 5.58. EIMS: m/z 243.1 (M+).

1,4-Bis(dimethyl (Z)-2-butenedioatoxy)benzene (4a). Whitesolid. mp 142–144 ◦C. 1H NMR (400 MHz, CDCl3): d 3.73 (s,6H, 2OCH3), 3.75 (s, 6H, 2OCH3), 6.56 (s, 2H, 2 HC C), 6.92(s, 4H, Ar–H). 13C NMR (100 MHz, CDCl3): d 52.02, 53.04

(4OCH3), 114.74 (2 CH), 117.45 (4CH), 149.99, 152.44 (4C),162.55, 163.88 (4C O, ester). IR (KBr, nmax, cm-1): 1724, 1503,1253, 1197. Elemental analysis for C18H18O10: Calc. C, 54.83; H,4.60. Found: C, 54.95; H, 4.69. EIMS: m/z 394 (M+).

1,3-Bis(dimethyl (Z)-2-butenedioatoxy)benzene (4b). Whitesolid. mp 70–72 ◦C. 1H NMR (400 MHz, CDCl3): d 3.72 (s,6H, 2OCH3), 3.76 (s, 6H, 2OCH3), 6.61 (s, 2H, 2 HC C), 6.59–7.25 (m, 4H, Ar–H). 13C NMR (100 MHz, CDCl3): d 52.04,53.07 (4OCH3), 104.95 (2 CH), 111.12, 115.38, 130.31, 157.54(C, CH-Ar), 149.43 (2 C), 162.41, 163.70 (4C O, ester). IR(KBr, nmax, cm-1): 1722, 1583, 1255, 1190. Elemental analysis forC18H18O10: Calc. C, 54.83; H, 4.60. Found: C, 54.75; H, 4. 49.EIMS: m/z 394 (M+).

1,4-Bis(diethyl (Z)-2-butenedioatoxy)benzene (4c). Yellowoil. 1H NMR (400 MHz, CDCl3): d 1.18 (t, 6H, J = 7.2, 2CH3),1.23 (t, 6H, J = 7.2, 2CH3), 4.18 (q, 4H, J = 7.2 Hz, 2OCH2),4.18 (q, 4H, J = 7.2 Hz, 2OCH2), 6.55 (s, 2H, 2 HC C), 6.92(s, 4H, Ar–H). 13C NMR (100 MHz, CDCl3): d 13.85, 14.04(4CH3), 60.95, 62.25 (4OCH2), 114.96 (2 CH), 117.39 (4CH-Ar), 150.13 (2 C), 152.51 (2C-Ar), 162.07, 163.51 (4C O,ester). IR (neat, nmax, cm-1): 1724, 1658, 1503, 1253, 1197.Elemental analysis for C18H18O10: Calc. C, 54.83; H, 4.60. Found:C, 54.92; H, 4.65. EIMS: m/z 450.1 (M+).

1,3-Bis(diethyl (Z)-2-butenedioatoxy)benzene (4d). Yellowoil. 1H NMR (400 MHz, CDCl3): d 1.18 (t, 6H, J = 7.2, 2CH3),1.22 (t, 6H, J = 7.2, 2CH3), 4.15 (q, 8H, J = 7.2 Hz, 4OCH2),6.59 (s, 2H, 2 HC C), 6.60–7.25 (m, 4H, Ar–H). 13C NMR(100 MHz, CDCl3) d 13.85, 14.00 (4CH3), 61.09, 62.31 (4OCH2),105.00, 110.93, 115.46, 130.08, 149.53, 157.90 (C, CH)), 161.70,163.32 (4C O, ester). IR (neat, nmax, cm-1): 1722, 1640, 1585,1253, 1190. Elemental analysis for C18H18O10: Calc. C, 54.83; H,4.60. Found: C, 54.85; H, 4.62. EIMS: m/z 450.1 (M+).

(Z)-Methyl 3-phenoxyacrylate (5a). Colorless oil. 1H NMR(400 MHz, CDCl3): d 3.79 (s, 3H, OCH3), 5.18 (d, 2H, J = 6.8 Hz,HC C), 6.90 (d, 2H, J = 7.2 Hz, HC C), 7.11–7.40 (m, 5H,Ar–H). 13C NMR (100 MHz, CDCl3): d 51.86 (CH3), 100.11,115.36, 117.64, 124.71, 129.53, 129.85, 154.15, 157.16 (CH, C),164.83 (C O, ester). IR (KBr, nmax, cm-1): 1729, 1630, 1450,1212, 1154. Elemental analysis for C10H10O3: Calc. C, 67.41; H,5.66. Found: C, 67.25; H, 5.56. EIMS: m/z 178.1 (M+).

(Z)-Methyl 3-(4-chlorophenoxy)acrylate (5b). Colorless oil.1H NMR (400 MHz, CDCl3): d 3.78 (s, 3H, OCH3), 5.23 (d,2H, J = 6.8 Hz, HC C), 6.85 (d, 2H, J = 7.2 Hz, HC C),7.03 (d, 2H, J = 9.2 Hz, Ar–H), 7.16 (d, 2H, J = 8.8 Hz, Ar–H). 13C NMR (100 MHz, CDCl3): d 51.58 (CH3), 99.94, 116.74,118.94, 129.37, 129.90, 154.24, 154.75, 155.46 (CH, C), 165.76(C O, ester). IR (KBr, nmax, cm-1): 1731, 1652, 1423, 1244,1121. Elemental analysis for C10H9ClO3: Calc. C, 56.49; H, 4.27.Found: C, 56.38; H, 4.15. EIMS: m/z 212.6 (M+).

(Z)-Methyl 3-(2-formylphenoxy)acrylate (5c). White solid.mp 82–85 ◦C. 1H NMR (400 MHz, CDCl3): d 3.79 (s, 3H,OCH3), 5.34 (d, 2H, J = 6.8 Hz, HC C), 7.01 (d, 2H, J =6.8 Hz, HC C), 7.14–7.96 (m, 4H, Ar–H), 10.58 (s, 1H, CHO).13C NMR (100 MHz, CDCl3): d 51.45 (CH3), 101.82, 116.33,124.86, 126.32, 128.60, 135.93, 151.99, 158.65 (CH, C), 164.70(C O, ester), 188.83 (CHO). IR (KBr, nmax, cm-1): 2824, 1739,

2856 | Green Chem., 2011, 13, 2851–2858 This journal is © The Royal Society of Chemistry 2011

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1720, 1644, 12251, 1161. Elemental analysis for C11H10O4: Calc.C, 64.07; H, 4.89. Found: C, 64.19; H, 5.01. EIMS: m/z 206.1(M+).

(Z)-Methyl 3-(phenylthio)acrylate (5d). Colorless oil. 1HNMR (400 MHz, CDCl3): d 3.79 (s, 3H, OCH3), 5.93 (d, 2H,J = 10 Hz, HC C), 7.29 (d, 2H, J = 10.4 Hz, HC C), 7.34–7.51 (m, 5H, Ar–H). 13C NMR (100 MHz, CDCl3): d 51.46(CH3), 112.19, 128.29, 129.39, 131.12, 136.04, 150.16 (CH, C),166.96 (C O, ester). IR (KBr, nmax, cm-1): 1734, 1638, 1457,1206, 1116. Elemental analysis for C10H10O2S: Calc. C, 61.83;H, 5.19. Found: C, 61.77; H, 5.27. EIMS: m/z 194.2 (M+).

(Z)-Methyl 3-(cyclohexylthio)acrylate (5e). Colorless oil. 1HNMR (400 MHz, CDCl3): d 1.26–2.03 (m, 10H, CH2), 2.83(tt, 1H, J = 10.8 Hz, J = 4 Hz, CH), 3.72 (s, 3H, OCH3),5.83 (d, 2H, J = 10.4 Hz, HC C), 7.18 (d, 2H, J = 10.4 Hz,HC C). 13C NMR (100 MHz, CDCl3): d 25.37, 25.82, 33.55,47.56 (CH, CH2), 51.18 (OCH3), 112.12, 148.73 (2 CH), 167.11(C O, ester). IR (KBr, nmax, cm-1): 1731, 1652, 1465, 1222,1119. Elemental analysis for C10H16O2S: Calc. C, 59.96; H, 8.05.Found: C, 60.06; H, 8.18. EIMS: m/z 200.3 (M+).

(Z)-Methyl 3-(piperidin-1-yl)acrylate (5f). Colorless oil. 1HNMR (400 MHz, CDCl3): d 1.55–1.63 (m, 6H, 3CH2), 3.19(br, 4H, 2CH2), 3.64 (s, 3H, OCH3), 4.61 (d, 1H, J = 13.2 Hz,

CH), 4.38 (d, 1H, J = 12.8 Hz, CH). 13C NMR (100 MHz,CDCl3): d 24.05, 25.40 (5CH2), 50.49 (OCH3), 83.19, 152.12 (2

CH), 170.59 (C O, ester). IR (KBr, nmax, cm-1): 1748, 1428,1217, 1160. Elemental analysis for C15H19NO4: Calc. C, 63.88;H, 8.93; N, 8.28. Found: C, 64.00; H, 8.89; N, 8.15. EIMS: m/z169.2 (M+).

(Z)-Ethyl 3-phenoxyacrylate (5g). Colorless oil. 1H NMR(400 MHz, CDCl3): d 1.32 (t, 3H, J = 7.0 Hz, CH3), 4.23 (q,2H, J = 7.2 Hz, 2OCH2), 5.18 (d, 1H, J = 6.8 Hz, CH), 6.90(d, 1H, J = 7.2 Hz, CH), 7.11–7.40 (m, 5H, Ar–H). 13C NMR(100 MHz, CDCl3): d 14.32 (CH3), 59.98 (CH2), 100.01, 115.36,117.64, 124.71, 129.53, 129.85, 154.15, 157.16 (CH, C), 164.83(C O, ester). IR (KBr, nmax, cm-1): 1745, 1621, 1426, 1231, 1118.Elemental analysis for C11H12O3: Calc. C, 68.74; H, 6.29. Found:C, 68.70; H, 6.35. EIMS: m/z 192.2 (M+).

(Z)-Ethyl 3-(cyclohexylthio)acrylate (5i). Colorless oil. 1HNMR (400 MHz, CDCl3): d 1.28 (t, 3H, J = 7.2 Hz, CH3), 1.32–2.03 (m, 10H, CH2), 2.83 (tt, 1H, J = 10.8 Hz, J = 4 Hz, CH),4.19 (q, 2H, J = 7.2 Hz, OCH2), 5.82 (d, 2H, J = 10 Hz, HC C),7.17 (d, 2H, J = 10.4 Hz, HC C). 13C NMR (100 MHz,CDCl3): d 14.36 (CH3), 25.39, 25.84, 33.56, 47.56 (CH, CH2),60.01 (OCH2), 112.56, 148.40 (2 CH), 166.76 (C O, ester).IR (KBr, nmax, cm-1): 1737, 1646, 1453, 1223, 1124. Elementalanalysis for C11H18O2S: Calc. C, 61.64; H, 8.47. Found: C, 61.70;H, 8.36. EIMS: m/z 214.3 (M+).

(Z)-Ethyl 3-(piperidin-1-yl)acrylate (5j). Colorless oil. 1HNMR (400 MHz, CDCl3): d 1.23 (t, 3H, J = 7.2 Hz, CH3), 1.57(m, 6H, 3CH2), 3.17 (m, 4H, 2CH2), 4.10 (q, 2H, J = 7.2 Hz,OCH2), 4.59 (d, 1H, J = 13.2 Hz, CH), 7.37 (d, 1H, J =13.2 Hz, CH). 13C NMR (100 MHz, CDCl3): d 14.63 (CH3),24.05, 25.39 (5CH2), 58.84 (OCH2), 83.19, 152.00 (2 CH),170.21 (C O, ester). IR (KBr, nmax, cm-1): 1751, 1648, 1433,1224, 1142. Elemental analysis for C15H19NO4: Calc. C, 65.54;

H, 9.35; N, 7.64. Found: C, 65.47; H, 9.28; N, 7.60. EIMS: m/z183.2 (M+).

Di-tert-butyl 2-(phenoxy)-2-butenedioate. Colorless oil.Mixture of Z:E isomer = 90 : 10; 1H NMR (400 MHz, CDCl3):d 1.34 (s, 9H, 3CH3), 1.42 (s, 9H, 3CH3), 1.46 (s, 9H, 3CH3),1.53 (s, 9H, 3CH3), 5.14 (s, 1H, HC C), 6.43 (s, 1H, HC C),6.95–7.42 (m, Ar–H). 13C NMR (100 MHz, CDCl3): d 27.63,27.99, 81.64, 83.22, 101.81, 116.02, 116.21, 120.75, 123.01,125.71, 129.44, 129.91, 150.15, 156.86, 161.34, 163.15. IR (KBr,nmax, cm-1): 1751, 1632, 1445, 1225, 1129. Elemental analysisfor C18H24O5: Calc. C, 67.48; H, 7.55. Found: C, 67.59; H, 7.61.EIMS: m/z 320.3 (M+).

Acknowledgements

We are grateful for the financial support of the University ofMazandaran, Islamic Republic of Iran.

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