A Highly Enantioselective Catalytic Mannich Reaction of Indolenines with Ketones

A range of polysubstituted indolenines (3H-indoles) smoothly underwent an L-proline-catalyzed enantioselective Mannich reaction with various ketones in a highly regioselective manner to give structurally diverse 2-acylmethylindolines in good yields with excellent ee. The current study provides a powerful approach for the transformation of unactivated five-membered cyclic aldimines into optically active nitrogen-containing heterocycles with high enantioselectivity.