Asymmetric induction in the Michael reaction by means of chiral phase-transfer catalysts derived from cinchona and ephedra alkaloids

Abstract

Asymmetric induction in the Michael reaction has been achieved using alkaloidonium salts in a two-phase system with optical yields of up to 36 and 26% in the addition to αβ-unsaturated ketones of thiols and nitroalkanes respectively. The presence of a hydroxy-group β to the 'onium function is essential to achieve substantial asymmetric syntheses.