Cu-catalyzed oxidative coupling of alkylarenes with tertiary C(sp3)–H bonds via C–H activation

Abstract

An efficient Cu-catalyzed cross-dehydrogenative coupling (CDC) of oxindoles, fluorenes and xanthenes with alkylarenes containing primary and secondary benzylic C–H bonds was developed. The method is capable of forming highly hindered bonds (adjacent quaternary/ternary centers) and permits direct access to highly functionalized oxindoles, fluorenes and xanthenes with good functional group compatibility. This oxidative protocol is operationally simple and the synthetic utility was demonstrated by a gram-scale reaction while maintaining the yield. Further synthetic transformations of this product proceeded in high yield. Based on observations from a radical capture experiment, the transformation is proposed to proceed via a radical process.