Direct access to 2-aminopyrazolo[1,5-a]pyridines via N-amination/cyclization reactions of 2-pyridineacetonitriles

Abstract We describe the straightforward synthesis of 6-substituted-2-aminopyrazolo[1,5- a ]pyridines from 2-pyridineacetonitriles by N- amination with O- (mesitylsulfonyl)hydroxylamine and subsequent base-promoted cyclization. This N- amination/intramolecular cyclization reaction allows access to a variety of 6-substituted-2-aminopyrazolo[1,5- a ]pyridines in a one-pot procedure, in moderate to good yields.