Synthesis and characterisation of benzyl phosphino-thioether and -thiolato Pd(ii) complexes and their applications in Suzuki coupling reactions
作者:Athanasia Dervisi、Despina Koursarou、Li-ling Ooi、Peter N. Horton、Michael B. Hursthouse
DOI:10.1039/b609607g
日期:——
The synthesis of the benzyl phosphinothioether derivatives Ph2PCH2CH(Et)SR and their corresponding palladium complexes are reported, where R = CH2Ph (3), R = CH2-3,5-Me-C6H3 (4) and R = 1-CH2C10H7 (5). Crystallographic data obtained for the complexes Pd(3)Cl2 and Pd(4)Cl2 show intra- and inter-molecular π–π interactions between the aromatic rings on the P and S substituents, and NOE experiments for Pd(4)Cl2 show that these interactions persist in solution. The performance of the phosphinothioether palladium complexes in aryl–aryl cross-coupling reactions is compared with that of the corresponding complex of the parent phosphinothiolato ligand Ph2PCH2CH(Et)S− (1). High turnover numbers up to 2000000 are reported for the coupling of bromobenzene, using the palladium dimer [Pd(1)I]2 as the catalyst precursor. Kinetic studies show a linear dependence of the reaction on catalyst loading. The effect of other variables on the cross-coupling reaction, such as temperature, solvent and base, is also reported.
报道了苄基膦硫醚衍生物Ph2PCH2CH(Et)SR及其相应的钯配合物的合成,其中R = CH2Ph (3),R = CH2-3,5-Me-C6H3 (4)和R = 1-CH2C10H7 (5)。针对配合物Pd(3)Cl2和Pd(4)Cl2获得的晶体学数据表明,在P和S取代基上的芳香环之间存在分子内和分子间的π-π相互作用,而针对Pd(4)Cl2的NOE实验显示这些相互作用在溶液中仍然存在。比较了膦硫醚钯配合物在芳香烃交叉偶联反应中的表现与母体膦硫醇配体Ph2PCH2CH(Et)S− (1)相应配合物的表现。在使用钯二聚体[Pd(1)I]2作为催化剂前体的情况下,溴苯的偶联反应报告了高达2000000的高周转数。动力学研究显示反应对催化剂负荷呈线性依赖关系。还报告了温度、溶剂和碱等其他变量对交叉偶联反应的影响。