Catalytic Asymmetric Mukaiyama-Mannich Reaction of Cyclic C-Acylimines with Difluoroenoxysilanes: Access to Difluoroalkylated Indolin-3-ones.

A catalytic enantioselective Mukaiyama-Mannich reaction of cyclic C-acylimines with difluoroenoxysilanes is reported. (S)-TRIP enables the enantioselective synthesis of a series of novel difluoroalkylated indolin-3-ones bearing a quaternary stereocenter in up to 97% yield and 98% ee. The synthetic utility of this protocol is highlighted by efficient conversion of the products to the corresponding indolin-3-one derivatives without any erosion of the enantiopurity.