Asymmetric aza-Henry reaction to provide oxindoles with quaternary carbon stereocenter catalyzed by a metal-templated chiral Brønsted base

Abstract

An asymmetric aza-Henry reaction between isatin-derived ketimines and aryl nitromethanes is catalyzed by an inert octahedral chiral-at-metal iridium(iii) complex which serves as a chiral Brønsted base. Initially, a kinetically favored diastereomer is formed with high diastereoselectivity and excellent enantioselectivity, and can be epimerized efficiently under base catalysis into the thermodynamically favored diastereomer. The work underscores the potential of our metal-templated approach for the design of high performance asymmetric catalysts.