Palladium-catalyzed annulation of diarylamines with olefins through C-H activation: direct access to N-arylindoles

Abstract

A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.

Keywords: CH activation; cyclization; indoles; palladium; reaction mechanisms.