Asymmetric Synthesis of 3-Alkyl 3-Alkyloxy-2-oxindoles by Enantioconvergent Alkoxylation with Alcohols

A highly enantioselective alkoxylation reaction of 3-bromo-3-substituted 2-oxindoles with alcohols was achieved by a chiral Ni(II)/N,N'-dioxide complex. This strategy provided an efficient route to various enantioenriched 3-alkyl 3-alkyloxy-2-oxindoles with good yield and er value (40 examples, up to 99% yield, 95/5 er). Moreover, phenol and benzenethiol were also compatible in the reaction. The gram-scale synthesis of optically active product and its further transformation to CPC-1 analogue demonstrated the potential utility of the method. In addition, a catalytic cycle as well as possible working mode was provided to understand the enantioselectivity of the reaction.