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Updated: Nov 4, 2025

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
Divergent and Regioselective Synthesis of Pyrazolo[1,5-a]pyridines and Imidazo[1,5-a]pyridines
Katrina M Mennie1, Michael H Reutershan1, Catherine White1
1Merck & Co., Inc., Boston, Massachusetts 02115, United States.
Abstract:
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.
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