Rhodium-Catalyzed Synthesis of 2-Methylindoles via C–N Bond Cleavage of N-Allylbenzimidazole

• DOI: 10.1021/acs.joc.2c03048
• Publication Date: 2023-05-24T12:01:21Z
• Authors: Pragati Biswal; Tanmayee Nanda; Namrata Prusty; Smruti Ranjan Moh...; Ponneri C. Ravikumar
• Keywords: Indoles; Rhodium; Oxidation-Reduction; Catalysis

A rhodium-catalyzed oxidative C-H/N-H dehydrogenative [3 + 2] annulation strategy has been reported between anilines and N-allylbenzimidazole for the synthesis of 2-methylindole scaffolds. An N-allylbenzimidazole has been used as a 2C synthon for the synthesis of indole, and more importantly, this transformation involves the cleavage of the thermodynamically stable C-N bond of allylamine. Detailed mechanistic studies have been performed and a key intermediate was detected in HRMS. This transformation proceeds through a cascade of C(sp2)-H allylation followed by intramolecular cyclization.