摘要
由于其强给电子能力、结构易修饰性和拓扑学特性,N-杂环卡宾成为继有机膦配体之后又一类重要的配体。其金属络合物在均相及不对称催化领域的催化性能是近期研究的热点,已有许多成功的结果。本文综述了近年来N-杂环卡宾及其金属络合物以及N-杂环卡宾的重要前体咪唑盐的合成方法。金属-N-杂环卡宾络合物的合成方法包括:(a)游离卡宾与金属化合物直接络合;(b)咪唑盐与金属化合物在强碱作用下络合;(c)利用Ag-NHC通过卡宾配体转移方法制备新的金属络合物。关于N-杂环卡宾前体的合成途径主要有:(a)乙二醛、伯胺和多聚甲醛的缩合反应;(b)卤代烷与咪唑或取代咪唑的烷基化反应;(c)原甲酸酯与1,2-二胺的成环反应;(d)肼或酰胺与酸酐的环化反应;(e)用Na/K对环硫脲化合物的还原反应。
Due to the strong electronic donor properties and the versatile structures which can be easily modified, as well as the distinct topography, N-heterocyclie carbene（NHC） is a new class of ligands as an alternative to traditional phosphine ones. Therefore, it is attractive to use NHC as ligand in catalysis. In fact, the catalytic properties of NHC- metal （NHC-M） complexes in homogeneous and asymmetric catalysis have been a focused research field and many successful results have been reported in recent years. In this paper, the syntheses of NHC, NHC-M complexes and their major precursor imidazolium salts are reviewed. The synthetic methods for NHC-M complexes include： （a） reaction of metal complexes with pre-formed NHC ligands; （b） reaction of metal complexes with NHC precursors such as imidazolium salts and a strong base; （c） interaction between metal halide and NHC-Ag complexes. For the synthesis of NHC precursors, there are also several routes： （a） condensation of glyoxal, amines and paraformaldehyde; （b） alkylation of imidazole or monosubstituted imidazole with alkyl halide; （c） annulation of ortho esters and 1,2-diamines; （d） ring closure of hydrazines or amides with acetic anhydride; （e） reduction of thiones with Na/K in THF.
出处
《化学进展》
SCIE
CAS
CSCD
北大核心
2009年第6期1229-1240,共12页
Progress in Chemistry
基金
国家自然科学基金项目(No.20672016)资助
