Cinchona-Based Primary Amine-Catalyzed Asymmetric Cascade Aza-Michael–Aldol Reactions of Enones with 2-(1<i>H</i>-Pyrrol-2-yl)-2-oxoacetates: Synthesis of Chiral Pyrrolizines with Multistereocenters

Abstract

Cinchona-based primary amine-catalyzed cascade aza-Michael-aldol reactions of α,β-unsaturated ketones with 2-(1H-pyrrol-2-yl)-2-oxoacetates provided highly functionalized chiral pyrrolizines bearing multistereocenters including a chiral quaternary carbon center in good yields (up to 92%) with excellent levels of stereocontrol (90-95% ee, >20:1 dr in all cases). The ketone group in the cascade product was asymmetrically reduced to chiral secondary hydroxyl groups in good yields.