Rapid and selective formation of Pyrazolo[1,5-a]pyridines and Imidazo[1,5-a]pyridines

Divergent and Regioselective Synthesis of Pyrazolo[1,5-a]pyridines and Imidazo[1,5-a]pyridines, by Katrina M. Mennie, Michael H. Reutershan, Catherine White, Bruce Adams , Bridget Becker, James Deng, Jason D. Katz, Elisabeth LaBlue, Kaila Margrey, and Josep Saurí. Org. Lett. 2021, 23, 12, 4694–4698. https://doi.org/10.1021/acs.orglett.1c01431

Nitrogenous heterocycles are ubiquitous in pharmaceuticals and drug-like compounds; however, regioselective synthesis has proved challenging. Herein we report our efforts to develop a regioselective method for the synthesis of pyrazolo[1,5-a]pyridines and the serendipitous discovery of a protocol for the regioselective formation of imidazo[1,5-a]pyridines. Together, these transformations allow for the rapid and selective formation of two important heterocyclic motifs from a common intermediate.