Organocatalytic Asymmetric Vinylogous Michael Addition of 3-(2-Oxoindolin-3-ylidene)butanoates to Nitroalkenes Catalyzed by a Bifunctional Cinchona-Based Squaramide

摘要

The highly efficient asymmetric vinylogous Michael addition of 3-(2-oxoindolin-3-ylidene)butanoates to nitroalkenes, catalyzed by a cinchona-based squaramide, is described. The enantioselectivity (up to 99% ee) and diastereoselectivity (>20:1d.r.) of the reaction is excellent.