Enantioselective Organocatalyzed Vinylogous Michael Reactions of 3-Alkylidene Oxindoles with Enals.

An efficient asymmetric vinylogous Michael addition of 3-alkylidene oxindoles and enals has been achieved using a chiral TBS-protected diphenylprolinol catalyst. The γ-substituted alkylidene oxindoles obtained bear a chiral tertiary center and are afforded in moderate to good yields and good to excellent enantioselectivities.