Organocatalysis with Chiral Formamides: Asymmetric Allylation and Reduction of Imines

Abstract

Abstract Simple aldimine, derived from p ‐nitrobenzaldehyde and 2‐aminophenol, reacts with allyltrichlorosilane in the presence of chiral N ‐formylproline activator 5 and an L ‐proline additive to afford the corresponding homoallylic amine in good yield (84 %) and with moderate enantioselectivity (43 % ee ). The role of the second formamide moiety in the activator is crucial to bring about the enhancement in the reaction rate and enantioselectivity, as C 2 ‐chiral bisformamide 1 promotes for the same allylation reaction in higher yield (94 %) and enantioselectivity (83 % ee ). Chiral monoformamide 5 (10 mol‐%), with the assistance of HMPA as an additive, also catalyses the asymmetric reduction of ketimine 13 in the presence of trichlorosilane in good yield and enantioselectivity (75 %, 81 % ee ). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)