Reactivity of cinnamonitriles with 2-cyano- and 2-ethoxycarbonylacetohydrazides: a novel one-step preparation and crystal structure of 3-oxopyrazolo [3,4-b]pyridines

Abstract

A novel one-step of pyrazolo[3,4-b] Pyridines 8 from α-benzoylcinnamonitriles and 2′-acetyl-2-cyanoacetohydrazide 2 is described. The X-ray crystallographic analysis revealed the presence of the enol tautomer and the existence of a strong network of hydrogen bobds. The use of 2-ethoxycarbobylacetohydrazide derivatives 12 as starting materials led only to the intermediate dihydro-2-pyridones 13. 2-Cyanoacetohydrazide 11 led to the novel triazolo [1,5-a]Pyridinones 15.