Abstract:

Asymmetric epoxidation of unfunctional olefin（styrene，α-methyl styrene，indene）was performed  with Jacobsen’s catalyst and silica gel supported (Salen)-Mn(Ⅲ) complex as catalysts（1,2），ionic liquids tetrafluoroborate（1-methyl-3-butyl imidazole）onium salt（BMIMBF₄）and hexafluorophosphate（1-methyl-3-butyl imidazole）onium salt（BMIMPF₆）as reaction medium，sodium，hypochlorite as oxidant，ammonium acetate as axial ligand. The results indicated that the ionic liquids were more effective for enhancing the conversion and enantiomeric excess than dichloromethane，and（BMIMPF₆）was better than（BMIMBF₄）. At the same time，the silica gel supported (Salen)-Mn(Ⅲ) complex demonstrated satisfactory enantioselectivity and activity even higher than homogeneous Jacobsen’s catalyst. Especially，in the epoxidation of a-methylstyrene，the enantiomeric excess in the BMIMPF₆ reached 100%，and could be recycled five times without obvious loss of activity.

摘要：

进行了以Jacobsen催化剂、硅胶型 (Salen)-Mn（Ⅲ）配合物为催化剂（1,2），以离子液体1-丁基-3-甲基咪唑四氟硼酸盐（BMIMBF₄）和1-丁基-3-甲基咪唑六氟磷酸盐（BMIMPF₆）为反应介质，次氯酸钠为氧化剂，乙酸铵为轴向配体催化非官能团烯烃（苯乙烯、α-甲基苯乙烯、茚）的不对称环氧化反应。通过实验对比发现，反应介质离子液体与二氯甲烷相比可以有效提高催化反应的速率和ee值，并且离子液体BMIMPF₆辅助催化能力高于（BMIMBF₄）；硅胶载体型配合物在离子液中催化烯烃具有比均相Jacobsen催化剂更好的立体催化效果。如a-甲基苯乙烯，在离子液BMIMPF₆反应中获到97%～100%的ee值，且反应循环5次后催化剂活性没有明显的下降。