total synthesis of cyclosporine: access to n-methylated
TRANSCRIPT
Total Synthesis of Cyclosporine:Access to N-Methylated Peptides via
Isonitrile Coupling ReactionsXiangyang Wu, Jennifer L. Stockdill, Ping Wang, Samuel J. Danishefsky*
Adam T. HoyeCurrent LiteratureMarch 27, 2010
J. Am. Chem. Soc. 2010,132, 4098-4100
N
OHN
O
NH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OOR OH
OC N R'
Me
Adam Hoye @ Wipf Group Page 1 of 24 4/26/2010
Historical perspective and hypothesis
Li, X.; Danishefsky, S. J. J. Am. Chem. Soc. 2008, 130, 5446-5448
Passerini reaction
N+R3
N+ CR1
R4
H
R3CHO + R4NH2
N+ CR1N
R3
R2 O
O
HR4
NR1
O
R2
O
HN
R3R4
H+NH
R1O
N
R3
OR21,4 O !N
acyl transfer R4
Ugi four-component coupling reaction
R
O
OHN+C R' N+ CR'
R O
O
H
N
O
R'
R
O??H
OR3
N+ CR1
N+ CR1OH
R3
R2 O
O
NR1
O
R2
O
OH
R3
NH
R1O
O
R3
OR2
H+
1,4 O !O
acyl transfer
Current hypothesis
Adam Hoye @ Wipf Group Page 2 of 24 4/26/2010
Initial discovery
Jones, G. O.; Li, X.; Hayden, A. E.; Houk, K., N.; Danishefsky, S. J. Org. Lett. 2008, 10, 4093-4096.
“concerted pseudopericyclic [1,3]-acyl rearrangement”
Ph NCHO Ph
ON
Ph
O
H
OPh
NO
Ph
O Ph
NPh
C
OO
Ph
microwave150 °C
CHCl3
[2 + 2]H
Ph
N
O H
O
Ph1,3 O !N
acyl transfer
83%
“Formamidine Carboxylate Mixed Anhydride”
N
Ph
O
H
OPh
Ph
N
O H
O
PhN O
H
O Ph
Ph
FCMA
N-formyl imide
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Probing reaction conditions
O
HO
NHFmoc
CO2t-Bu
NC N
HO
O NHFmoc
CO2t-Bumicrowave150 °C
CHCl3
82%
O
HO
NHFmoc
CO2t-Bu
NCCHCl3
rt, 24 h
no detectablereaction
MeONH2
O NHFmoc
CO2t-BuHN
OMe
rt, 24 h10-15%
O
HO
NHFmoc
CO2t-Bu
NC
MeONH2
microwave130 °C, 30 min
CHCl3N
HO
O NHFmoc
CO2t-BuHN
O NHFmoc
CO2t-Bu O NHFmoc
CO2t-BuHN
OMe
1.3 : 1.0 : 2.0
N O
H O NHFmoc
CO2t-Bu
Li, X.; Danishefsky, S. J. J. Am. Chem. Soc. 2008, 130, 5446-5448
common intermediate
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Application to asparagine-linked glycopeptides
Anomerically-specificglycosidic imidations
α
β
O
BnOBnO
BnOOBn
NC
FmocHN CO2t-Bu
CO2H
CHCl3, µW, 150 °C, 30-45 min
O
BnOBnO
BnOOBn
NOHC
O NHFmoc
CO2t-Bu
85%
OX
OBnBnO
BnOOBn
X = N3
X = NC
1. i. Pd/C, H2, ii.
2. triphosgene, 75%
OHO O
FmocHN CO2t-Bu
CO2H
O
OBnBnO
BnOOBn
NCHO
O
CO2t-Bu
NHFmocCHCl3, µW,
150 °C, 30-45 min85%
OX
AcOAcO
AcON3
X = N3
X = NC
1. i. (NH4)MoS4 ii.
2. triphosgene, 90%
OHO O , 53%
O
N3
NCHO
O
CO2t-Bu
NHFmoc
AcOAcO
AcO
FmocHN CO2t-Bu
CO2H
CHCl3, µW, 150 °C, 30-45 min
82%
ON C
AcOAcO
AcON O
H
OAcO
AcOAcO
AcHN
O
O
NHFmoct-BuO2CFmocHN CO2t-Bu
CO2H
CHCl3, µW, 150 °C, 30-45 min
50%
H+
Also see: Li, X.; Danishefsky, S. J. Nat. Protoc. 2008, 3, 1666-1670
Glycosidic esterification
Adam Hoye @ Wipf Group Page 5 of 24 4/26/2010
N-Formyl imide manipulations
DeformylationPh N
CHOPh
O
Ph NH
Ph
ONaOMe, MeOH
quant.
Reduction
Tertiary N-Me amides!
O
OBnBnO
BnOOBn
NCHO
O
CO2t-Bu
NHFmoc
O
OBnBnO
BnOOBn
HN
O
CO2t-Bu
NHFmoc
NaOMe, MeOH
quant.
N
O NHFmoc
CO2t-BuR
R = CHO
R = CH2OH
NaBH4,MeOH
85%
TFA, Et3SiH
CH2Cl2 90%
N
O NHFmoc
CO2t-BuMe
O
OBnBnO
BnOOBn
NR
O
CO2t-Bu
NHFmoc
R = CHO
R = CH2OHNaBH4,MeOH
TFA, Et3SiH
CH2Cl2 52% (2 steps)
O
OBnBnO
BnOOBn
NMe
O
CO2t-Bu
NHFmoc
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N-Formyl imide manipulations
Further functionalization
Ph NCHO
Ph
O1. NaBH4, MeOH
2. TFA, allylTMSPh N Ph
O
64%
Li, X.; Danishefsky, S. J. J. Am. Chem. Soc. 2008, 130, 5446-5448
O
HO Ph
O
cy-NC N
O
CHOOPh
CHCl3
150 °C, 30 min75%
NO
Ph
O
1. LiHMDS, THF
2. TFA, CH2Cl275%
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Mechanistic investigations
Li, X.; Yuan, Y.; Kan, C.; Danishefsky, S. J. J. Am. Chem. Soc. 2008, 130, 13225-13227
R1
O
OH R1 O
O
NR2
R1 O
O
R1
O
NH
R2H
O
R1 O
O
HNR2
R1
O
NR2
CHO
1,3 O !Nacyl transfer
O-acylation
N-acylation
R1 O
O N
H
R2 1,3 O !Nacyl transfer
R1
O
NR2
CHOR1
O
O
HC N+ R2
NO2
CO2H NC
NO2
O O N Ph
NO2
O NCHO
Ph
CHCl3µW, 150 °C
85%
O OO
O2N NO2
NHCHO
CHCl3µW, 150 °C
16%
NO2
O NCHO
Ph -Anhydride mechanism could be minorcontributor to mechanism
-Possibility of anydride conversion to FCMAand acyl transfer
“Formamidine Carboxylate Mixed Anhydride”
FCMA
FCMA
Adam Hoye @ Wipf Group Page 8 of 24 4/26/2010
Iterative isonitrile couplings
Li, X.; Yuan, Y.; Kan, C.; Danishefsky, S. J. J. Am. Chem. Soc. 2008, 130, 13225-13227
NPhth O
NHMe
Me
CO2H
CN CO2t-Bu
Ph
CHCl3, µW, 150 °C30 min
NPhth O
NHMe
Me
O
O
N CO2t-Bu
Ph
NPhth
Me
Me
O
N
O
H2OSM
N CO2H
Me
Me
O
O
CO2t-Bu
CN
DCE, µW, 160 °C30 min
70%
NPhth O
NCHOMe
Me
CO2R
CN CO2t-Bu
Ph
CHCl3, µW, 150 °C30 min41%
(2 steps)R = t-Bu
R = HHCO2H
NPhth O
NR1Me
Me
N
O
R2
Ph
CO2t-Bu
R1, R2 = CHO
R1, R2 = H
NaHCO3,MeOH60%
Adam Hoye @ Wipf Group Page 9 of 24 4/26/2010
Interception of FCMA
NH
CO2Bn
CO2H
Boc
NCCHCl3
150 °C,µW
MeOHOMe
O
CO2BnHNBoc
N
O
CO2BnHNBoc
CHONH
O
CO2BnHNBoc
MeOH,µW
38%
41%
30%
14%
4%
11%
1 eq.
5 eq.
NH
CO2Bn
CO2H
Boc
NC
NH
CO2BnBoc
O
O
N
NC
MeOH
NH2
NH
O
CO2BnHNBoc
?
Rationale:
Solution: need better (faster) acyl donorfor successful interception of FCMAintermediate
“sacrificial isonitrile”
Adam Hoye @ Wipf Group Page 10 of 24 4/26/2010
Sulfur effect
Rao, Y.; Li, X.; Danishefsky, S. J. J. Am. Chem. Soc. 2009, 131, 12924-12926Yuan, Y.; Zhu, J.; Li, X.; Wu, X.; Danishefsky, S. J. Tetrahedron Lett. 2009, 50, 2329-2333
R1 SH
OC N+ R2
RT
R1 S
O
H
NR2
R1 N
O
H
S
R2
RT
oxo-FCMA formation and rearrangement
thio-FCMA formation and rearrangment
R1 OH
OC N+ R2
RT
R1 O
O
H
NR2 µW
R1 N
O
H
O
R2
NH
MeMe
Fmoc
O
N
S
CO2Bn
Me Me
NH
MeMe
Fmoc
O
N
S
CO2Bn
Ph
NH
Fmoc
O
N
S
CO2Bn
OO
Me
NH
Fmoc
O
N
S
CO2Bn
Me Me
t-BuO
NH
Fmoc
O
HN CO2Bn
Me Me
t-BuO
1. mCPBA
2. NaHCO3, MeOH
80% (2 steps)
60%(82% brsm)
50%
63%
59%1.0 eq. thioacid
1.0 eq. isonitrile
CHCl3
RT12 h
thio-FCMA
Room temp.acyl shift
More reactive, butbetter acyl donors?
Adam Hoye @ Wipf Group Page 11 of 24 4/26/2010
Sulfur effect
COSHFmocHN
CO2Allyl
C N+ Cy
DCM, RT
DCM, RT
Ph-NH2
FmocHN
CO2Allyl
O
NCHS
FmocHN
CO2Allyl
O
NH
Ph HN
H
S
55%
75%
COSHFmocHN
CO2Allyl
C N+ t-Bu
DCM, RT
DCM, RT
Ph-NH2
FmocHN
CO2Allyl
O
NCHS
FmocHN
CO2Allyl
O
NH
Ph
77%
not observed
HNS
H
t-Bu
HNS
H
t-Bu
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Substrate scope
Rao, Y.; Li, X.; Danishefsky, S. J. J. Am. Chem. Soc. 2009, 131, 12924-12926
Secondary amides Tertiary amides
R1 SH
OC N+ t-Bu
RT
R1 S
O
H
Nt-Bu
R1 N
OR3
R2FAST
vs.S = O
HNR2
R3 S
NHt-BuH
Adam Hoye @ Wipf Group Page 13 of 24 4/26/2010
Substrate scope
FmocHN
MeSH
O
C N+ t-BuDCM
RTFmocHN
MeS
OC
N t-Bu
H
O H
MeMe
FmocHN
MeO
O
Me
Me
O
O
Me
MeBocHN
BnO2C64%
43%
Esterification
Tertiary amide formation
FmocHNSH
O
C N+ t-Bu
Me Me
MeHN CO2H
MeMe
MeHN CO2Me
MeMe
(3.0 eq.)
DCM, RT
DCM, RT
(3.0 eq.)
FmocHNS
O
Me MeH
Nt-Bu
MeHNMe
Me
OHO
FmocHNO
O
Me Me
O
Me
Me
NHMe
FmocHNN
O
Me Me
CO2H
Me Me
MeFmocHNN
O
Me Me
CO2Me
Me Me
MeTMSCH2N2
90%
1,4 O !Nacyl transfer75%
Adam Hoye @ Wipf Group Page 14 of 24 4/26/2010
Cyclosporine A
Corey, E. J.; Czakó, B.; Kürti, L. Molecules and Medicine; Wiley: Hoboken, NJ, 2007; p. 124
· Fungal metabolite from Tolypocladium inflatum gams· Initially isolated in early 1960s at Sandoz (later Novartis) in Basel, Switz.· Narrow antibiotic activities, shelved until 1970s· Crude fungal extract inhibited lymphocyte proliferation w/out affecting
somatic cells· Structure reported in 1976 (chem degradation, NMR, X-ray)· Dr. Thomas E. Starzl (Univ. of Pittsburgh) established clinical utility of
cyclosporine in liver transplants (preventing organ rejection) in 1982-landmarks around Pitt campus
· Acts by inhibiting cytokines (via calcineurin) that stimulate growth,differentiation, and survival of T-cells.
N
OHN
O
NH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OO
Me
Adam Hoye @ Wipf Group Page 15 of 24 4/26/2010
Previous syntheses of cyclosporine A
Synthesis: Wenger, R. M. Helv. Chim. Acta. 1984, 67, 502-525SAR studies: Wenger, R. M. Angew. Chem. Ind. Ed. Engl. 1985, 24, 77-138
Colucci, W. J.; Tung, R. D.; Petri, J. A., Rich, D. H. J. Org. Chem. 1990, 55, 2895-2903Rich, D. H.; Sun, C.-Q.; Guillaume, D.; Evans, D. A.; Weber, A. E. J. Med. Chem. 1989, 32, 1982-1987Galpin, I. J.; Mohammed, A. K. A.; Patel, A. Tetrahedron 1988, 44, 1783-1794
· Total synthesis reported by Wenger in 1984
· Unusual amino acid (MeBmt) critical to activity; considerable attention,synthetically
· Bioavailability (proteolysis) dependent on N-Me amide pattern in 7 of 11amide bonds (SAR crucial) (Wenger, Rich, Galpin)
N
OHN
O
NH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OO
Me
Adam Hoye @ Wipf Group Page 16 of 24 4/26/2010
Retrosynthetic analysis
N
OHN
O
NH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OO
OH
O
MeO
NMe
N
O NHBoc
NO
Me
Me
N
OOOBn
Me
O
NH
ON
O
NH
ON
O
Me
Me
NMe
O
BocHN
BnO
Me
peptidecoupling
peptidecoupling
peptidecoupling
peptidecoupling
macrolactamization
A
B
C
Adam Hoye @ Wipf Group Page 17 of 24 4/26/2010
Fragment A
Grieco, P. A.; Bahsas, A. J. Org. Chem. 1987, 52, 5746-5749
BocHNO
SHCN
O
OBn1. CHCl3
2. Bu3SnH, AIBN 100 °C, PhMe
62% (2 steps)
BocHNO
NMe
OBn
O
1. CH2Cl2, TFA
NO
NMe
OBn
O
2. cyclopentadiene H2O, HCHO
3. Et3SiH, TFA
52%(3 steps)
HCl·HNO
NMe
OBn
O
Me
NO
NMe
OBn
O
H
BocHNO
SH CNO
OBnN
O
OBn
Me
OBocHN
1. CHCl3
2. Bu3SnH, AIBN 100 °C, PhMe
59% (2 steps)
1. H2, 10% Pd/C, MeOH
2. DEPBT, DIPEA, THF, dipeptide
NO
NMe
OBn
O
Me
ONMe
OBocHN
90%(2 steps)
dipeptide
A
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Fragment B
Evans, D. A.; Weber, A. E. J. Am. Chem. Soc. 1986, 108, 6757-6761
B
NO
O O
NCSBn
O
HMe
Me
Sn(OTf)2, N-ethyl piperidine,THF, -78 °C
NO
O O
NCSBn
OSnL
R
NO
O O
BnHN
O
S
Me
Me
73%2. Me3O+·BF4
-
1. MgOMe, MeOH
MeO
O
NO
SMe
Me
Me
Me
MeO
O
NO
O
Me
Me
H2O
74-86%
KOH
H3O+
70% OH
O
MeO
NMeMe
MeO2C
NHMeOH
Me1. acetonide formation
2. saponification
Route by Evans and Weber:
Adam Hoye @ Wipf Group Page 19 of 24 4/26/2010
Fragment C
N3
O
OHCN
Ot-Bu
ON
Ot-Bu
OCHO
ON3
DCE
155 °CµW85%
NHN
OCHO
ON3 OBn
O1. HCOOH
2. HCl·H2N-Ala-OBn, HATU, DIPEA, DMF
81% (2 steps)
1. LiBH4, CH2Cl2, n-PrOH, Ac2O, -50 °C
2. TF2O, Et3SiH,CH2Cl2, -50 °C62% (2 steps)
NHN
OMe
ON3 OBn
O PPh3, THF, H2O
75% NHN
OMe
OH2N
OBn
O
NHN
OMe
OHN
OBn
O
OTFA·HN
Me
1. Boc-MeLeu-OH, HATU, DIPEA, DMF
2. TFA, CH2Cl282% (2 steps)
tetrapeptide
C
BocHNSH
OTsOH·HN
Me
OBn
O
BocHNO
NMe O
OBn
Cy NC
CHCl380%
BocHNO
NMe O
SH
1. Pd/C, H2, MeOH100%
2. Lawesson's reagent, CH2Cl2
65%
NHN
OMe
OHN
OBn
O
ONMe
ONMe
OTFA·HN
1. Cy-NC, CHCl3, tetrapeptide
2. TFA, DCM63%
(2 steps)
Adam Hoye @ Wipf Group Page 20 of 24 4/26/2010
Completion of cyclosporine
OH
O
MeO
NMe
NHN
OMe
OHN
OBn
O
ONMe
ONMe
ONH
OHN
HO Me
Me
NHN
OMe
OHN
OBn
O
ONMe
ONMe
OTFA·HN
1. DCC, HOBt, NMM, THF
2. HCl (aq.), MeOH
NO
NMe
OBn
O
Me
ONMe
OBocHN
1. H2, Pd/C, MeOH
75% (2 steps)
PyBOP, NMM, CH2Cl252% (2 steps)
N
ONH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OO
Me
NHBoc
BnOO
C
B
A
Adam Hoye @ Wipf Group Page 21 of 24 4/26/2010
Completion of cyclosporine
N
ONH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OO
Me
NHBoc
BnOO
1. NaOH (aq.), EtOH2. TFA, CH2Cl2, -20 °C
3. Cy-NC, HOBt, CH2Cl2, 70 °C, µW
54%(3 steps)
N
OHN
O
NH
ON
O
NH
ON
O
Me
Me
NMe
O
HN
ON
Me
MeN
OMe
Me
NHO
OO
Me
19 steps (longest linear)3.5%* overall yield
Adam Hoye @ Wipf Group Page 22 of 24 4/26/2010
Conclusions· Synthesis of cyclosporin in a fashion that allows for more detailed
mapping of SAR
· Excellent showcase of methodology- power and diversity(N-formyl imide and acyl transfer chemistry)
· Thiol effect in mechanism (acyl donor capabilities)
· Diversity of N-formyl imide products
· Application to glycopeptides
O
OBnBnO
BnOOBn
NCHO
O
CO2t-Bu
NHFmoc
O
BnOBnO
BnOOBn
NOHC
O NHFmoc
CO2t-BuO
AcOAcOAcO
AcHN
O
O
NHFmoct-BuO2C
R1NCHO
R2
O
R1NH
R2
ONaOMe, MeOH
1. NaBH4, MeOH
2. TFA, allylTMS
R1N R2
O
NO
Ph
O
R1NMe
R2
O
i. NaBH4,MeOH
ii. TFA, Et3SiH
Adam Hoye @ Wipf Group Page 23 of 24 4/26/2010
Conclusions
Rao, Y.; Li, X.; Danishefsky, S. J. J. Am. Chem. Soc. 2009, 131, 12924-12926
“We note in passing that amines, isonitriles, and thioacids are very oldfunctional groups which go back to the beginnings of organicchemistry. The amide forming construction described here could, inprinciple, have been conducted in 1909 without difficulty. It is notunlikely that careful mechanistically based revisitation of thefoundations of organic chemistry might yield additional surprises ofconsiderable value”
Adam Hoye @ Wipf Group Page 24 of 24 4/26/2010