A Divergent Approach to the Diastereoselective Synthesis of 3,3-Disubstituted Oxindoles from Atropisomeric N-Aryl Oxindole Derivatives.

3,3-Disubstituted oxindoles were divergently synthesized by diastereoselective transformations including nucleophilic addition, alkylation, and cycloaddition using common, axially chiral N-aryl oxindoles. Notably, high diastereoselectivities (up to >95:5) were observed with ortho-monosubstituted N-aryl oxindoles to give various oxindole scaffolds, and facile removal of the p-(benzyloxy)aryl moiety in axially twisted amides was achieved by a mild, two-step sequence.