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The use of N-alkyl-2,2'-bipyrrolidine derivatives as organocatalysts for the asymmetric Michael addition of ketones and aldehydes to nitroolefins

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Published in Advanced Synthesis and Catalysis. 2004, vol. 346, no. 9-10, p. 1147-1168
Abstract The direct Michael addition of aldehydes and ketones to nitroolefins, catalyzed by N-i-Pr-2,2'-bipyrrolidine, is described. The desired 1,4-adducts are obtained in excellent yields with enantioselectivities up to 95% ee and dr up to 95 : 5 of the syn aldehyde addition product. An unexpected inversion of diastereoselectivity was observed for the addition of a-hydroxy ketones to ß-arylnitroolefins with enantioselectivities up to 98% ee. The formation of an internal hydrogen bond between the OH group of the a-hydroxy ketone and the tertiary nitrogen of the catalyst leads to the formation of a rigid cis enamine intermediate that accounts for the inversion of the expected diastereoselectivity and the very high ees.
Keywords AminesAsymmetric catalysisConjugate additionNitroolefinsOrganocatalysis
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Note Special Issue : Organic Catalysis
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ANDREY, Olivier et al. The use of N-alkyl-2,2'-bipyrrolidine derivatives as organocatalysts for the asymmetric Michael addition of ketones and aldehydes to nitroolefins. In: Advanced Synthesis and Catalysis, 2004, vol. 346, n° 9-10, p. 1147-1168. https://archive-ouverte.unige.ch/unige:8215

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Deposited on : 2010-06-21

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