The synthesis of N-alkyl-1H-1,2,4-triazoles from N,N-dialkylhydrazones and nitriles via formal [3+2] cycloaddition including the C-chlorination/nucleophilic addition/cyclisation/dealkylation sequence was developed. This sequential reaction utilising the in situ generation of hydrazonoyl chloride based on the ambiphilic reactivity of hydrazones afforded a variety of multi-substituted N-alkyl-triazoles
Formamidine anions in synthesis. The one-carbon homologation of aldehydes and ketones to nitriles
作者:Braulio Santiago、A.I. Meyers
DOI:10.1016/s0040-4039(00)73793-2
日期:1993.9
Treatment of various carbonyl compounds with the carbanion of the 2-trimethylsilymethyl formamidine 2 gives the enamidine 3 which is readily transformed into the homologated nitriles 6.
Treatment of tantalum-alkyne complexes with dimethylhydrazones by the assistance of Me 3 Al in a mixed solvent of DME, benzene, and THF at 45°C for 16 h gives (E)-allylic hydrazines stereoselectively
在二甲醚、苯和四氢呋喃的混合溶剂中,在 Me 3 Al 的帮助下,在 45°C 下用二甲基腙处理钽-炔配合物 16 小时,立体选择性地得到 (E)-烯丙基肼
1,2-Reduction of α,β-unsaturated hydrazones using dimethylamine–borane/p-toluenesulfonic acid: an easy route to allyl hydrazines
作者:Maria E Casarini、Franco Ghelfi、Emanuela Libertini、Ugo M Pagnoni、Andrew F Parsons
DOI:10.1016/s0040-4020(02)00914-6
日期:2002.9
alpha,beta-Unsaturated hydrazones can be easily converted into N-allyl hydrazines by reaction with dimethylamine-borane/p-toluenesulfonic acid under mild reaction conditions. The reduction works well for N'-allyhydrazides but N'-allyl-N,N-dimethylhydrazines are rapidly reoxidised by air and so need to be manipulated under an inert atmosphere prior to M-acylation. Competitive conjugate reduction can also be observed and the regioselectivity of the dimethylamine-borane attack is determined by steric and/or electronic factors. The procedure is also effective for the C=N reduction of unconjugated hydrazones. (C) 2002 Elsevier Science Ltd. All rights reserved.