Heterocyclic Synthesis With Azides. I. The Reaction of Hydrazoic Acid With Ethoxymethylenemalonate

Abstract

Reaction of diethyl ethoxymethylenemalonate with sodium azide in trifluoroacetic acid at 20� gives ethyl 5-ethoxyisoxazole-4-carboxylate (67%), diethyl cyanomalonate (21%) and diethyl ethoxyaminomethylenemalonate (5%). The last compound and its tautomer are converted into ethyl 1-ethoxy-3-oxo-2,3-dihydro-1H-pyrazole-4-carboxylate. The product structures have been confirmed by synthesis or degradation.