Bifunctional Cinchona Alkaloid Squaramide Catalyzed Highly Enantioselective Aza-Michael Addition of Indolines to α,β-Unsaturated Ketones.

An enantioselective aza-Michael addition of indolines to α,β-unsaturated ketones was achieved using a bifunctional cinchona alkaloid-derived chiral squaramide derivative. Various β-indolinyl ketone derivatives were obtained in good to excellent yields and with high enantioselectivity. DDQ or MnO2 oxidation of indoline derivatives provided convenient access to various enantioenriched N-substituted indole derivatives.