Synthesis of pyrazolo[1,5-a]pyridines by thermal intramolecular cyclization

Thermal intramolecular cyclization of N-amino-2-alkynylpyridines was developed for facile and versatile synthesis of pyrazolo[1,5-a]pyridines. Simply heating N-amino-2-alkynylpyridines in acetic acid provided pyrazolo[1,5-a]pyridines in excellent yield. (C) 2013 Elsevier Ltd. All rights reserved.