N-杂环卡宾(NHC)是一种特殊类型的卡宾,其中卡宾碳原子是氮杂环的一部分。由于其合成的简单性和立体电子性质的模块化,NHC无疑已经成为化学科学中最迷人和最著名的物种之一。NHC的显着稳定性可归因于其结构特征引起的动力学和热力学效应。NHC构成有机金属化学中公认的一类新配体。尽管最初NHC被认为是纯σ供体配体,后来的实验和理论研究确定了从金属的d轨道到NHC的π*轨道的大量回赠。在过去的二十年里,NHC-金属络合物已被广泛用作不同类型的有机反应中的有效催化剂。其中,NHC-Cu(I)配合物因各种原因而突出,例如易于准备,结构多样性的可能性,低成本,和多功能的应用。本文综述了近12年来NHC-Cu(I)配合物作为催化剂在有机合成中的应用,其中包括氢化硅烷化反应,共轭加成,[3+2]环加成,A3反应,硼化和硼氢化,N-H和C(sp2)-H羧化,C(sp2)-H链烯基化和烯丙基化,C(sp2)-H芳基化,C(sp2)-H酰胺化,和C(sp2)-H硫醇化。在应用部分之前,简要描述NHCs的结构,NHC-金属键的性质,提供了制备NHC-Cu络合物的方法。
N-Heterocyclic carbenes (NHCs) are a special type of carbenes in which the carbene carbon atom is part of the nitrogen heterocyclic ring. Due to the simplicity of their synthesis and the modularity of their stereoelectronic properties, NHCs have unquestionably emerged as one of the most fascinating and well-known species in chemical science. The remarkable stability of NHCs can be attributed to both kinetic as well as thermodynamic effects caused by its structural features. NHCs constitute a well-established class of new ligands in organometallic chemistry. Although initially NHCs were regarded as pure σ-donor ligands, later experimental and theoretical studies established the presence of a significant back donation from the d-orbital of the metal to the π* orbital of the NHC. Over the last two decades, NHC-metal complexes have been extensively used as efficient catalysts in different types of organic reactions. Of these, NHC-Cu(I) complexes found prominence for various reasons, such as ease of preparation, possibility of structural diversity, low cost, and versatile applications. This article overviews applications of NHC-Cu(I) complexes as catalysts in organic synthesis over the last 12 years, which include hydrosilylation reactions, conjugate addition, [3 + 2] cycloaddition, A3 reaction, boration and hydroboration, N-H and C(sp2)-H carboxylation, C(sp2)-H alkenylation and allylation, C(sp2)-H arylation, C(sp2)-H amidation, and C(sp2)-H thiolation. Preceding the section of applications, a brief description of the structure of NHCs, nature of NHC-metal bond, and methods of preparation of NHC-Cu complexes is provided.