Microwave-assisted organic synthesis: The Gabriel approach as a route to new pyrazolylhydrazonoazoles

Abstract

The pyrazole 7 was diazotized in the presence of hydrochloric acid in acetic acid to give in situ the diazonium chloride 9. The latter was coupled with malononitrile to afford 2-pyrazolylhydrazonomesoxalonitrile 10, which could be converted into aminopyrazolone 11 by reaction with hydrazine hydrate. The phenylhydrazone 13 reacted with hydroxylamine hydrochloride to afford the oxime 18 that could be readily converted into the nitrile 19 either by refluxing in a solution of sodium acetate in acetic acid or by heating in a microwave oven (MW). Compound 19 reacted with hydroxylamine hydrochloride to give amidooxime 20 either by refluxing in dioxane or by heating in MW. © ARKAT USA, Inc.