Pentanidium Catalyzed Hydroxylation of Oxindoles with Air

Abstract

Asymmetric hydroxylation of 3-substituted oxindoles under phase-transfer condition was developed. Good yield and excellent enantiomeric excess were achieved. It was demonstrated that this reductant free condition is actually a two-step reaction. The first step is the hydroperoxidation of the 3-substituted oxindoles followed by kinetic resolution of the hydroperoxide to give the final product with excellent enantiomeric excess.