Synthesis of phenanthridines via a palladium-catalyzed annulation of 2-iodobenzimines with 2-halobenzoic acids

Abstract

A palladium-catalyzed decarboxylative annulation reaction of 2-iodobenzimines with 2-halobenzoic acids has been developed for the synthesis of phenanthridine scaffolds. Density functional theory calculations revealed that in the presence of the KOAc additive, this annulation reaction proceeds via a Pd(II) transmetalation pathway rather than the oxidative Pd(IV) formation pathway. The base Cs₂CO₃ plays a crucial role in C–H bond activation, which is the rate-determining step.