环(烷基)(氨基)卡宾及其在烯烃复分解反应中的研究展望

Cyclic(alkyl)(amino)carbenes and the Research Prospect in Olefin Metathesis Reaction

烯烃复分解反应是形成碳碳双键的重要反应之一,其发展与结构明确的钌催化剂[L2X2Ru=CHR]中配体的创制密切相关.1999年,环二氨基卡宾配体的引入极大提高了催化剂的活性、稳定性以及官能团适用性.2005年,Bertrand等发展了一种比环二氨基卡宾具有更强给电子能力的配体──环(烷基)(氨基)卡宾(CAACs)配体,且卡宾中心α位为一季碳原子,这使得其空间环境与其他类型卡宾配体有很大差异.首先概述了CAACs配体的合成及性质,紧接着讨论了其在烯烃复分解催化反应中的研究进展,最后对该领域所存在的问题进行简要分析并对其发展作了展望.

Olefin metathesis has been one of the most important methods to construct carbon-carbon double bonds, which has been enabled by development of well-defined transition-metal catalysts （e.g. [L2X2Ru = CHR], L = PCy3）. A significant gain to increase the catalyst stability and activity was achieved after replacing a single PCy3 ligand of L2X2Ru----CHR （L=PCy3） with cyclic biamino cabene, such as 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene （H2IMes）. In 2005, Bertrand et al. discovered a novel ligand-yclic（alkyl）（amino）cabene （CAAC）, which displayed more electron donating and more electrophilic in comparison with cyclic diamino cabene. It is logic that more electronegative amino group is replaced by alkyl group in CAAC. Furthermore, a quaternary carbon at the a position of carbene center of CAAC may make a big difference from cyclic diamino cabene, which can change the steric environment of CAAC easily and treat a chiral center next to the carbene. In this research prospect, synthesis, property and application of CAACs in olefin metathesis catalysis are introduced. Finally, the issues remained in this research area are summarized and an outlook for the develonment in the future is given.