介孔分子筛MCM-41负载钯催化剂催化合成α-芳基酮化合物的研究

MCM-41 supported palladium catalyst for synthesis of α-aryl ketones

以芳基酮和溴代芳烃为原料,介孔分子筛MCM-41负载钳形钯配合物为催化剂,研究了一种制备α-芳基酮化合物的方法.结果表明:在催化剂用量1.0%,反应时间2 h,反应温度81℃的条件下,负载型钯催化剂可以高效催化生成α-芳基酮化合物,产率可达94%.该反应官能团兼容性好,底物范围广,催化剂重复使用5次,活性未出现明显降低.

α-aryl ketone compounds are an important part of many drugs and biologically active molecules,and have important applications in the fields of organic synthesis and medicinal chemistry.Among the reported synthesis methods ofα-aryl ketone compounds,the transition metal palladium catalyzedα-arylation of halogenated aromatic compounds is a highly selective and environmentally friendly synthesis method,and has been a research hotspot in modern organic synthesis.However,most of the catalyst systems are homogeneous catalysts in the form of palladium-ligands,which are difficult to recover and increase the reaction cost from an industrial perspective,and many ligands are unstable and need to be in an inert gas atmosphere to effectively catalyze the reaction.In addition,the residual palladium will cause pollution to the product,which is a problem that cannot be ignored in pharmaceutical synthesis.In view of economical and ecological respect,heterogeneous catalysts possess obvious merits on account of the easy-separation after the completion of reactions.Combination of high selectivity and activity of homogeneous catalysts with easy-separation,catalyst recovery of heterogeneous catalysts would be expectable to reach an ideal catalyst system.Mesoporous molecular sieve MCM-41 has a large specific surface area(700~1500 m^(2)·g^(-1))and pore volume(greater than 0.6 cm^(3)·g^(-1)),as well as a hexagonal structure and one-dimensional straight pores.A large number of silanol groups are distributed,which can be modified by the silane coupling agent and further combined with a homogeneous catalyst to form a highly active,recyclable supported catalyst.In this paper,a supported catalyst is designed and synthesized by using mesoporous molecular sieve MCM-41 as the carrier,the palladium complex as the active component.The structure of the catalyst is characterized by FT-IR,X-ray powder diffraction,elemental analysis and nitrogen physical adsorption.The catalyst was applied in the synthesis ofα-aryl ketone compounds with aryl ketones and brominated aromatic hydrocarbons as the raw materials.The results show that the supported palladium catalyst can efficiently catalyze the synthesis ofα-aryl ketone compounds with the highest yield of 94%,under the optimal conditions of catalyst dosage 1.0%,reaction time 2 h,and reaction temperature 81℃.The catalyst system has good functional group tolerance and wide range of substrates.The catalyst has been reused for 5 times without obvious decrease in activity.The catalytic system realizes the combination of the homogeneous catalyst and the inorganic carrier,thereby achieving the green reaction process to a large extent.