ORGANIC
LETTERS
2007
Vol. 9, No. 21
4339-4341
Ir-Catalyzed Regio- and Enantioselective
Decarboxylative Allylic Alkylations
Hu He, Xiao-Jian Zheng, Yi Li, Li-Xin Dai, and Shu-Li You*
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic
Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received August 9, 2007
ABSTRACT
[Ir(COD)Cl]2/phosphoramidite ligand 1a was found to be an efficient catalytic system for the highly regio- and enantioselective decarboxylative
alkylation of -substituted allyl -ketocarboxylates, affording the branched products with up to >99/1 branched-linear ratio and 96% ee.
γ
â
Transition-metal-catalyzed asymmetric allylic alkylation
(AAA) has become one of the most efficient ways to
construct carbon-carbon bonds with stereocenters.1 Although
high enantioselectivities could be achieved with soft nucleo-
philes and symmetrical allylic substrates, particularly, with
a palladium catalyst, enantioselectivity with ketone enolates
as nucleophiles2 and regioselectivity related to unsymmetrical
allylic substrates3 remain challenging. Recently, Hartwig and
co-workers reported the Ir-catalyzed highly regio- and
enantioselective allylations of silyl enol ethers or enamines
to tackle both of the problems.4 As high enantioselectivities
were obtained for palladium-catalyzed decarboxylative allylic
alkylations involving ketone enolates generated in situ,5-7
we envisaged that highly regio- and enantioselective allyl-
ation of ketone enolates might be achieved through decar-
boxylative allylic alkylation of allyl â-ketocarboxylates in
(1) Reviews: (a) Trost, B. M.; Van Vranken, D. L. Chem. ReV. 1996,
96, 395. (b) Trost, B. M. Acc. Chem. Res. 2002, 35, 695. (c) Trost, B. M.;
Crawley, M. L. Chem. ReV. 2003, 103, 2921.
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(b) Weix, D. J.; Hartwig, J. F. J. Am. Chem. Soc. 2007, 129, 7720.
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2005, 9, 1715. (b) You, S.-L.; Dai, L.-X. Angew. Chem., Int. Ed. 2006, 45,
5246.
(6) For recent examples: (a) Burger, E. C.; Tunge, J. A. Org. Lett. 2004,
6, 4113. (b) Kuwano, R.; Ishida, N.; Murakami, M. Chem. Commun. 2005,
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B. M.; Xu, J. J. Am. Chem. Soc. 2005, 127, 17180. (e) Mohr, J. T.; Behenna,
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(f) Nakamura, M.; Hajra, A.; Endo, K.; Nakamura, E. Angew. Chem., Int.
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2001, 3, 149. (d) Trost, B. M.; Schroeder, G. M. Chem.sEur. J. 2005, 11,
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L.-X.; Hou, X.-L. Angew. Chem., Int. Ed. 2005, 44, 6544. (f) Be´langer, E.;
Cantin, K.; Messe, O.; Tremblay, M.; Paquin, J.-F. J. Am. Chem. Soc. 2007,
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(3) (a) Pre´toˆt, R.; Pfaltz, A. Angew. Chem., Int. Ed. 1998, 37, 323. (b)
You, S.-L.; Zhu, X.-Z.; Luo, Y.-M.; Hou, X.-L.; Dai, L.-X. J. Am. Chem.
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(7) For a Ru-catalyzed enantioselective Carroll rearrangement, please
see: Constant, S.; Tortoioli, S.; Mu¨ller, J.; Lacour, J. Angew. Chem., Int.
Ed. 2007, 46, 2082.
10.1021/ol7019394 CCC: $37.00
© 2007 American Chemical Society
Published on Web 09/14/2007