Strategy for the Synthesis of pyrazolo[5,1-d][1,2,5]triazepinones, a new heterocyclic system

Abstract

A preparative procedure has been developed for the synthesis of 4-oxo-7-phenyl-5,8-dihydro-4H-pyrazolo[ 5,1-d][1,2,5]triazepine-2-carbohydrazide, the first representative of a new heterocyclic system, by recyclization of methyl 4-oxo-6-phenyl-4H-pyrazolo[5,1-c][1,4]oxazine-2-carboxylate with hydrazine hydrate.