Decomposition and cycloaddition reactions of some bis(azodicarbonyl) compounds

Abstract

During oxidation of 1,5-dibenzoylcarbonohydrazide and 1,6-dibenzoyloxalohydrazide with N-bromosuccinimide and pyridine evidence was obtained for the formation of the corresponding bisazo-compounds (4a and b). Both oxidations yielded the oxadiazolone (6), which was the main product in the former. The oxalohydrazide reaction also gave minor products, perhaps attributable to the intermediacy of benzoyldi-imide. Oxidation of 1,7-dibenzoylmalonohydrazide led to intractable mixtures.

Oxidation of 1,8-dibenzoylsuccino- and 1,10-dibenzoyladipo-hydrazides and of the bisethoxycarbonyl and dipivaloyl derivatives of terephthalohydrazide gave the fairly stable bisazo-compounds (5a–d) which could be trapped as the meso- and racemic mixture of bisadducts with cyclopentadiene (7a–d). The stereochemical possibilities for the concerted rearrangement of such adducts to bis-1,3,4-oxadiazines are fully discussed. In the adducts (7a and b) only participation of the outer (benzoyl) group and in the ester adduct (7c) only participation of the inner (tetraphthaloyl) group was observed, a diastereomeric pair of structures being produced in each case. The dipivaloyl adduct (7d) showed all three possible modes of isomerisation, utilising both inner and outer acyl groups; one of the pair of diastereoisomers formed was isolated pure in each case.