In Situ Formed Bifunctional Primary Amine-Imine Catalyst: Application to the Construction of Chiral Tertiary Alcohols through Asymmetric Aldol-Type Reaction

摘要

An in situ formation method to obtain chiral bifunctional primary amine-imine catalysts from the C2-symmetric chiral diimines has been developed. The efficiency of this method in the construction of chiral tertiary alcohols which are valuable pharmaceutical intermediates is proved by its application to the asymmetric aldol-type reaction of cyclic ketones with other activated ketone compounds as the enamine acceptors, i.e., β,γ-unsaturat-ed α-keto esters and isatins. In general, good to ex- cellent diastereoselectivities and enantioselectivities (up to 96/4 dr, 96% ee for β,γ-unsaturated α-keto esters and up to 91/9 dr, 94% ee for isatins) were obtained. The active primary amine-imine catalylst and enamine intermediate in the reaction process could be demonstrated by ESI-MS analysis.