Palladium-Catalyzed Imidoylative Cyclization of Tryptophan-Derived Isocyanides: Access to β-Carbolines

A palladium-catalyzed imidoylative cyclization of ethyl-3-(1H-indol-3-yl)-2-iSocyanopropanoates, derived from readily available tryptophan, to afford, beta-carboline derivatives has been developed. The reaction proceeds smoothly under mild conditions through sequential isocyanide insertion, intramolecular C-H imidoylation, and aerobic dehydrogenative aromatization with a decent substrate scope. This method provides a general approach for the synthesis of molecules containing the beta-carboline fragment.