Regioselective Functionalization of 4-Methyl-1H-indole for Scalable Synthesis of 2-Cyano-5-formyl-4-methyl-1H-indole

We report a five-step synthesis of 2-cyano-5-formyl-4-methyl-1H-indole through sequential functionalization of readily available 4-methyl-1H-indole. Cyano and aldehyde functionalities are regioselectively installed at the 2 and 5 position, respectively. The sequence is concise and high-yielding, amenable for kilogram scale production.