Reduction of hydrazines to amines with low-valent titanium reagent

Abstract

The N,N bond cleavage in hydrazines to amines via low-valent titanium reagent prepared in situ by treatment of TiCl4 with Mg powder in THF or CH2Cl2-Et2O is described. The reaction proceeds smoothly under mild conditions to afford amines in good to excellent yields with diverse functional group tolerance such as chloride, methoxyl, benzyloxyl, ester, acyl, as well as C,C double bonds and benzyl-nitrogen bonds.

Computational Study on N–N Homolytic Bond Dissociation Enthalpies of Hydrazine Derivatives

“…Hydrazine and derivatives have been used in many technical and commercial areas due to their unique characteristics. Some simplest hydrazines, for example, monomethylhydrazine (MMH) and unsymmetrical dimethylhydrazine (UDMH), which have significant thermochemical properties of very high heat of combustion, can serve as common rocket propellants for space applications. − Hydrazine derivatives are also classical and versatile building blocks in organic chemistry for the synthesis of biologically active N-containing heterocycle compounds such as α,β-diamino acids and monocyclic β-lactams. − Besides, the amines − obtained directly from hydrazine derivatives can be utilized as precursor materials for synthetic drugs − and can be regarded as target molecules for the synthesis of xerographic, photographic materials, conducting polymers, etc. One of the most important hydrazine derivatives, the hydrazides, are common intermediates obtained in a growing number of synthetic routes and widely used in synthesizing active nitrogen-containing molecules, such as the α-amino acids and peptides and their derivatives, which are versatile building blocks for the construction of important biological and pharmaceutical units …”

Zinc-Mediated Allylation and Benzylation of Phenylazocarboxylic Esters

“…In another one-pot procedure, the removal of the Boc-group from 3j by trifluoroacetic acid was combined with a copper-mediated intramolecular amination to give indazole 15 in 90% yield . The reductive cleavage of the N–N bond of the hydrazine can be performed directly after benzylation of the azo compound without intermediate workup . For the purpose of obtaining amine 16 from 1c and 2a , however, additional zinc powder, trifluoroacetic acid, and elevated temperatures over longer reaction times were required in the second step.…”

Facile titanium(IV) chloride and TBD‐mediated synthesis of N‐aryl‐substituted azacycles from arylhydrazines

“…When TiCl 4 and TBD were used for reaction of phenylhydrazine at 120 C, the N N bond of phenylhydrazine was cleaved to afford aniline, while the reaction of phenylhydrazine at lower temperatures such as room temperature did not provide aniline. Based on these results and previous reports, 22 a plausible pathway for the synthesis of N-aryl-substituted azacycles from arylhydrazine was proposed as depicted in Scheme 1. Phenylhydrazine 1a was treated with TiCl 4 to give aniline 6 and NH 3 .…”