Copper(II)-catalyzed molecular rearrangements: the behaviour of arylhydrazones of some 3-benzoylazoles in the presence of copper(II) acetate

Abstract

The reactivity of arylhydrazones of some 3-benzoylazoles (1,2,4-oxadiazole, isoxazole and 1,2,5-oxadiazole) induced by copper(II) catalysis has been investigated. In the 1,2,4-oxadiazole and isoxazole systems, copper(II) acetate monohydrate in methanol effectively induces molecular rearrangements of the arylhydrazones into the corresponding 1,2,3-triazoles, that is, without competitive oxidation processes. In the 1,2,5-oxadiazole series, no ring transformation occurs by the action of the same salt, the expected rearrangement into triazole oximes being achieved rather with sodium ethoxide in ethanol.