Pd-N-杂环卡宾化合物催化的Heck反应、Suzuki反应进展

Pd催化的C—C键偶联反应是形成碳—碳单键的重要反应之一.传统上,使用膦化合物为配体来调整催化活性及选择性.但大多数Pd-膦化合物对空气稳定性差,容易被氧化;在溶液中易于解离出膦配体而降低催化剂稳定性,通常需要给反应体系中加入较多的膦配体以保持催化剂的稳定性和活性.1991年发现的稳定N-杂环卡宾(NHC)类配体具有富含电子、给电子能力强,对金属配位能力强,结构易修饰等特点,使得金属-NHC化合物成为金属有机化学、催化等领域研究新的焦点.Pd-NHC化合物已经可催化多类有机反应,是继传统Pd-膦催化剂外的又一类高效催化剂.综述了近年来不同结构的NHC如单齿简单NHC、双齿NHC、含其它配位原子的NHC等配体与Pd的配合物在Heck反应、Suzuki反应等偶联反应中的应用.

Progress in the Heck Reaction and Suzuki Reaction Catalyzed by Pd-N-Heterocyclic Carbene Complexes

The C—C cross coupling reaction catalyzed by palladium complexes represents one of the most important C—C bond formation reactions. Traditionally, organo phosphines are used as the ligands to modify the catalytic properties of palladium complexes. However, most of them are air-sensitve, Labile to be oxidized and to dissociate in solution. Therefore, excess phosphorous ligands are needed to keep the catalytic activities. N-Heterocyclic carbene (NHC) reported since 1991 has been a focus in organometallic chemistry and catalysis because of its strong electronic donor properties, versatile structures that can be readily modified, and excellent coordinative ability to metal. The Pd-NHC compound has emerged as an al-ternative of Pd-phosphine compound in the promotion of C—C bond coupling reactions. In this paper, the application of the Pd-NHC complexes derived from mono-ligated NHC, chelate NHC to Heck reaction and Suzuki reaction was summarized.