Rhodium Catalyzed Stereoselective Mono-alkenylation of Aryl sp2 C-H Bond via C-N Bond Cleavage: N-allylbenzimidazole as Strategic Alkenylating Agent

Abstract

A Rh-catalyzed C(sp2)-H alkenylation has been achieved by taking N-allylbenzimidazole as an allylamine congener. This distinctive transformation has been observed for the first time which is attributed to the rigid benzimidazole unit. Lewis acid assisted cleavage of C(sp3)-N bond by coordinating to the N3 of N-allylbenzimidazole has been established. Thus, herein we have demonstrated an unprecedented protocol of domino C-N bond cleavage followed by aryl C(sp2)-H alkenylation. Further, detailed mechanistic studies, control experiments have been conducted to understand the mechanism. The rhodacycle-intermediates involved in the reaction have been isolated and characterized through NMR, HRMS, and single crystal X-ray.