Asymmetric Mannich reactions of beta-keto esters with acyl imines catalyzed by cinchona alkaloids

Abstract

Cinchona alkaloids catalyze the enantioselective Mannich reaction of beta-keto esters with acyl aryl imines. The reaction requires 10 mol % of cinchonine or cinchonidine. The reaction products are obtained in good yields (81-99%), high enantioselectivities (80-96% ee), and in diastereoselectivities that range from 1:1 to >95:5. The cinchonine-catalyzed reaction provides access to highly functionalized building blocks used in the asymmetric synthesis of a dihydropyrimidone and beta-amino alcohol.