synthesis of substituted imidazoles via organocatalysis - ccc/upcmld
TRANSCRIPT
Synthesis of Substituted Imidazoles viaOrganocatalysis
Doug E. Frantz, Louis Morency, Arash Soheili, Jerry A. Murry,Edward J. J. Grabowski, and Richard D. Tillyer
Department of Process Research,Merck Research Laboratories,
Merck & Co.
Michael Rishel @ Wipf Group 1 3/27/04
Imidazoles as Targets in Medicinal Chemistry
N
N
N
N
HN
N
N
N
NNH
NN
OH
Cl
Losartan
N
NNH
O
SO3H
O
N
CO2H
O PO3H2
Orally available Angiotensin IIinhibitor -- Lilly
R1
R2
RR2
R1
X
N
N
N
X
Y
Imidazole CSAID Ligands -- SKB
N
N
HOOC
COOH
S
Eprosartan
p38 MAP kinase inhibitors
Michael Rishel @ Wipf Group 2 3/27/04
Debus Reaction
Debus imidazole synthesis
RR
O
O
O
R' H+
NH3
H2O NH
NR'
R
R
Debus, H. Liebigs Ann. Chem. 1858, 107, 199.
reaction provides 2- monosbstituted, and 2,(3,4 homo)trisubstitutedimidazoles
Michael Rishel @ Wipf Group 3 3/27/04
Proposed Mechanism of the Debus Reaction
RR
NH
NH
NH
R' H+
HNR
R
N
R'
H2N
H
NN
R
R
HR'
NH3
HN
NR'
R
R
Michael Rishel @ Wipf Group 4 3/27/04
Wallach Reaction
NH
HN R
O
O
RPCl5, POCl3
heat
Wallach chloroimidazole synthesis
Wallach, O. Ber. Dtsch. Chim. Ges. 1881, 14, 420.
N
N
Cl
R
R
II
Provides 1,2 disubstituted chloroimidazoles
Michael Rishel @ Wipf Group 5 3/27/04
Proposed Mechanism of the Wallach Reaction
N
N
Cl
R
R
NH
HN R
O
O
R
PCl5N
N RR
Cl
Cl
-Cl-
+Cl-
N
N
R
Cl
R
-H+
+H+
N
N
R
Cl
R
+H+
-H+
N
N
R
R
ClH
H
-H+
+H+Cl
N
N
H
RH
R
+H+
-H+Cl
N
N
R
R
+Cl- -Cl-
+Cl--Cl-
NN R
R
Cl
H
NN R
R
Cl
H H Cl
HCl
-Cl-
-Cl- II
II
I
I
Benincori, T.; Brenna, E.; Sannicolo, F. J. Chem Soc. Perk. Trans. I 1993, 675-679.
Michael Rishel @ Wipf Group 6 3/27/04
TosMIC Based Imidazole Synthesis
Synthesis from TosMIC
R'' NC
SO
O
TosMIC = tosylmethyl isocyanide
N
R
R'+
van Leusen, A. M.; Wildeman, J.; Oldenziel, O. H. J. Org. Chem. 1977, 42, 1153-9
1. NaH, DME2. H2O3. K2CO3, MeOH N
N
R'R
R'' Process regioselectively provides 1,5-di and a limited number of 1,4,5-trisubstituted imidazoles
Michael Rishel @ Wipf Group 7 3/27/04
Mechanism of TosMIC based Imidazole Synthesis
R''
NS
OO
C
N
R
R'+ [3+2]
NS
OO
R''R
NR N
N
R'R
R''
SO
O
+
Michael Rishel @ Wipf Group 8 3/27/04
Extension of the TosMIC Chemistry
Horne, D. A.; Yakushijin, K.; Buchi, G. Heterocycles, 1994, 139
NC
SO
O O
R+
H
O
N
R
SO
OR''NH2
N
N
R''
R
An Extension of the TosMIC chemistry
R'
R' = H or AlkR'' = H or AlkR and R' cannot both = Alk
R'
R'
Process regioselectively provides 4, 1,4, and 4,5mono- and disubstituted imidazoles
1,4,5 trisubstituted imidazoles are not easily madewith this methodology as a regioisomeric mixture of products results.
Michael Rishel @ Wipf Group 9 3/27/04
Modified TosMIC Imidazole Mechanism
O
N
R
SO
O R''NH2
R'
O
N
R
R'
NHR''R''NH2
O
NH
R
NHR''R''HNH
heat
HNNHR''OHR
NR''
+when R' = H
when R' = alk
O
NH
R
AlkNR''
N
N RHO
N HN
R''NH
R''
H2O
N
NHR''
N+
R
R''H
H
R''NH2
N
N+
R
R''H
H
HN
N
R
R''
HH
R''R
Alk
?
Michael Rishel @ Wipf Group 10 3/27/04
Synthesis of Imidazoles from Amidines
Selective synthesis of 1,2,5 substituted imidazoles
NH
R NHR' X
OR''
Br
X = CHO, CN
+K2CO3
CHCl3, H2ON
NR'
R
X
major
N
NR'
R
minor
+
modest yields, good selectivityammenable to the synthesis ofmultikilogram quantities of pharmaceutical intermediates
X
Shilcrat, S. C.; Mokhallalati, M. K.; Fortunak, J. M. D.; Pridgen, L. N. J. Org. Chem. 1997, 62, 8449.
Michael Rishel @ Wipf Group 11 3/27/04
Imidazoles from Amidines -- Mechanism
NH
R NHR' X
OR''
Br
+ N
R NHR'
XR''O
BrH
N N
R
R'
XHR''O
N N
R
R'
X
major
minor R'N
R NH
XR''O
BrH
N N
R
R'
X
Michael Rishel @ Wipf Group 12 3/27/04
Imidazole carboxylates from BICAs
1,5 imidazole carboxylates from amines and 3-bromo-2-isocyanoacrylates (BICAs)
R
Br
NC
COOMe
R'NH2
DMF, Et3NN
N
R'
COOMe
R
Nunami, K.-I.; Yamada, M.; Fukui, T.; Matsumoto, K. J. Org. Chem. 1994, 59, 7635.
Complementary to the amidine methodology
Michael Rishel @ Wipf Group 13 3/27/04
BICA Mechanism
R
Br
NC
COOMeR'NH2 +
NC
COOMe
A
B
R
NC
COOMeR'HN
R'HN
H
R
NC
COOMeR'N H
R
NC
COOMeR'HNR
NHR'
R
N
COOMeR'HN
N
HN
C
COOMe
R'R
N
N COOMe
R'R
Michael Rishel @ Wipf Group 14 3/27/04
Hetero Cope Rearrangement -- A Strategy to HighlySubstituted Imidazoles
Hetero-Cope Rearrangements to regioselectively provide highly Substituted imidazoles
Lantos, I.; Zhang, W.-Y.; Shui, X,; Eggleston, D. S. J. Org Chem. , 1993, 58, 7092.
R
NR'OH
NR''
Cl Ph+
R
NR'O
Ph NHR''
R''N Ph
N
NR1
R2
R3
Ph
highly regioselective synthsis of tetrasubstituted imidazoles. Limited by R-group requirements.
Michael Rishel @ Wipf Group 15 3/27/04
Mechanism of the Hetero Cope RearrangementApproach
R
NR'O
Ph NR''
N Ph R
NR'O
Ph NR''
R''N Ph
R''R
NR'O
Ph NHR''
R''N Ph
R
NR'O
Ph N+
R''N Ph
H
R''
H
R
NR'
R''N Ph
O
Ph NHR''N
NR1
R2
R3
Ph
PhCONHR''
Michael Rishel @ Wipf Group 16 3/27/04
Highly Substituted Imidazoles From b-Ketoamides
Regioselective synthesis of tetrasubstuted imidazoles from b-ketoamides under neutral reaction conditions
N
O
R2
O
R1
N
X
ammonium trifluoroacetateN
N
R2
R1
N
X
Methodology tolerates variance at positions 1,2 and 5 quite well.
Position 4 usually, but not always, aromatic.
Claiborne, C. F.; Liverton, N. J.; Nguyen, K. Tetrahedron Lett. 1998, 39, 8939.
Michael Rishel @ Wipf Group 17 3/27/04
Synthesis of b-Ketoamides… Nontrivial??
Michael Rishel @ Wipf Group 18 3/27/04
A Traceless Synthesis of b-Ketoamides
OO
H1. RNH22. LiBH4 O
HN R1
R3R2
O
X
ON R1
R2
R3
O
R4 Cl
O
OCl
R4 NR3
O
O
R1
R2
+
N
N
R1
R2
R3
R4
Lee, H. B.; Balasubramanian, S. Org. Lett. 2000, 2, 323.
A traceless entry into b-ketoamides -- and tetrasubstituted imidazoles
Michael Rishel @ Wipf Group 19 3/27/04
Thiazolium Catalyzed Synthesis of b-Ketoamides
O
HR1 R2 NH
R3
SO2Tol
+
SN OHR4
X
Et3N, CH2Cl2 35 oC
R2HN R3
OOR1
Murry, J. A.; Frantz, D. E.; Soheili, A.; Tillyer, R.; Grabowski, E. J. J.; Reider, P. J. Am.Chem. Soc. 2001, 9696.
Michael Rishel @ Wipf Group 20 3/27/04
Mechanism of b-Ketoamide Synthesis byOrganocatalysis
Murry, J. A.; Frantz, D. E.; Soheili, A.; Tillyer, R.; Grabowski, E. J. J.; Reider, P. J. J. Am. Chem. Soc. 2001, 123, 9696.
Michael Rishel @ Wipf Group 21 3/27/04
Regioselective, “One Pot” Synthesis of SubstitutedImidazole
Michael Rishel @ Wipf Group 22 3/27/04
One-Pot Synthesis of Di- andTrisubstituted Imidazoles
Michael Rishel @ Wipf Group 23 3/27/04
Synthesis of Tetrasubstituted Imidazoles
Michael Rishel @ Wipf Group 24 3/27/04
Application to the Synthesis of Substituted Oxazolesand Thiazoles
Michael Rishel @ Wipf Group 25 3/27/04
Conclusions
• A rapid, one-pot, regioselective, organocatalyzed synthesis of highlyfunctionalized imidazoles from b-ketoamides has been described
• The methodology has been extended to the synthesis of substitutedoxazoles and thiazoles
Michael Rishel @ Wipf Group 26 3/27/04