H. Tavakol and A. Heydari,  Preparation of trisubstituted hydrazines from aldehydes  12^th Iranian seminar of Organic Chemistry, Ahwaz jundi shapour university of medical science, Ahwaz, Iran, 7-9 March 2006

Abstract

Although in recent years there has been a growing interest in reductive amination reacvtions^1-4, but only a few reports have been reviewed that used hydrazones in these reductive amination methods for preparation of hydrazines from amino reduction reactions.

In these reactions, at first, one synthesize hydrazones from the condensation reaction between aldehydes or ketones with hydrazine hydrate or substituted hydrazines and then reduce them to corresponding substituted hydrazines.

By using reductive method in synthesis of hydrazines, we prevent some problems arises from other methods such as polyalkylation in direct alkylation of hydrazines with alkylating agent. During the course of our investigations dealing with the use of Boran complexes^5,6 for reduction of C=N double bonds in one-pot multicomponent reaction starting from aldehydes, an attempt was made to utilize Boran complex for the same purpose and preparation of hydrazines from aldehydes by using Boran-Triethylamine as a reducing agent in one-pot reductive amination. In our researches, we succeed at in situ preparation of hydrazones from condensation reaction between N,N- Dimethylhydrazine and various aldehydes in good yield, and then reduced them to corresponding hydrazines. Both two steps are carried out in one vessel and in presence of Lithium Perchlorate and Trimethylsilylchloride as a catalyst in Diethyl Ether solution. In scheme 1, we report the common reaction that in all cases, the reactions proceeded smoothly at ambient temperature with reasonable yield in 2h.