Chemical Development of the Casein Kinase I - Epsilon Inhibitor: 3-(3-Fluorophenyl)sulfanyl-1H-pyrrolo[3,2-b]pyridine-2-carboxylic Acid Amide

The development of a scalable process for 3-arylsulfanyl-1H-pyrrolo[3,2-b]pyridine-2-carboxylic acid amides (1), potent casein kinase I inhibitors, is described. The rapid identification of suitable reaction conditions expedited the lab scale synthesis of drug substances for early toxicological evaluations. Further improvements were made to achieve a safe and cost-effective process to meet increasing demands for drug substances to support clinical studies. This paper describes the synthesis at multikilogram scale.