Asymmetric Construction of 3,3-Disubstituted Oxindoles Bearing Vicinal Quaternary-Tertiary Carbon Stereocenters Catalyzed by a Chiral-at-Rhodium Complex.

A highly diastereo- and enantioselective synthesis of 3,3-disubstituted oxindoles bearing vicinal quaternary-tertiary carbon centers is enabled by a chiral-at-rhodium Lewis acid catalyst starting from isatin N-protected ketimines and 2-acyl imidazoles. The excellent results with 93-99% yields, diastereoselectivities of 43:1 to >200:1, and high enantioselectivities of 98.4 to >99% confirm the potential of bis-cyclometalated rhodium catalysts for the development of effective asymmetric transformations.