Pyrazolopyridines. Part IV. Preparation and tautomerism of 6-cyano- and 6-ethoxycarbonyl-1,4-dihydropyrazolo[4,3-b]pyridin-7-ones

Abstract

6-Cyano- and 6-ethoxycarbonyl-1,4-dihydropyrazolo[4,3-b]pyridin-7-ones have been prepared by cyclisation of pyrazol-4-ylaminomethylene-cyanoacetates and -malonates respectively. Cyclisation occurs preferentially at the 5-position of the pyrazole ring. The 6-ethoxycarbonyl compounds have been shown to exist in the pyridone form by comparison with model compounds.