Reactions of hydrazones and hydrazides with Lewis acidic boranes

Abstract

The reaction of (diphenylmethylene)hydrazone or 1,4-bis-hydrazone-ylidene(phenylmethyl)benzene with Lewis acidic boranes B(2,4,6-F₃C₆H₂)₃ or B(3,4,5-F₃C₆H₂)₃ generates the Lewis acid–base adducts. Alternatively, when (9H-fluoren-9-ylidene)hydrazone is employed several products were isolated including 1,2-di(9H-fluoren-9-ylidene)hydrazone, the 2 : 1 borane adduct of NH₂–NH₂ and the 1-(diarylboraneyl)-2-(9H-fluoren-9-ylidene)hydrazone in which one ArH group has been eliminated. The benzhydrazide starting material also initially gives an adduct when reacted with Lewis acidic boranes which upon heating eliminates ArH generating a CON₂B heterocycle.