Immobilization Of Chiral Mn(salen) Catalysts In Nanopores And On Surface Of Solid Supports And The Asymmetric Epoxidation Of Unfunctionalized Olefins

The heterogeneous asymmetric catalysis has received more and more attentions in recent years. Among all the reactions, the heterogeneous asymmetric epoxidation is most impressive. Chiral Mn(salen) catalysts have been axially immobilized onto various supports for the asymmetric epoxidation of unfunctionalized olefins. The various factors influencing the heterogeneous catalysts are also investigated in detail. The main results of the thesis work are describled as follows.The method for the immobilization of the Mn(salen) catalysts via phenoxy groups is improved. Chiral Mn(salen) catalysts were also successfully immobilized via organic sulfonic groups. Several chiral Mn(salen) catalysts were axially immobilized in the nanopores and on the external surface of mesoporous materials, as well as on insoluble polymers via phenoxy groups and organic sulfonic groups. These heterogeneous Mn(salen) catalysts can give higher TOF, cis/trans ratio and enantioselectivity than those of the homogeneous catalysts for the asymmetric epoxidation of some unfunctionalized olefins. For examples, heterogeneous catalyst gives higher TOF (14.8 h-1 vs 10.8 h-1) and ee values (90.6% vs 80.1%) than those of the homogeneous catalyst for the asymmetric epoxidation of 6-cyano-2, 2-dimethylchromene; another heterogeneous catalyst shows higher cis/trans ratio (17.6 vs 0.38) and ee values (94.6% vs 54.8%) than those of the homogeneous catalyst for the asymmetric epoxidation of cis-β-methylstyrene.The various factors of the heterogeneous Mn(salen) catalysts that might affect the heterogeneous asymmetric epoxidation are investigated in detail. The Mn(salen) catalysts immobilized in the nanopores can generally improve the chemical selectivity and enantioselectivity compared to the catalysts immobilized on the external surface of supports for the asymmetric epoxidation of unfunctionalized olefins. The Mn(salen) catalysts grafted via flexible propyl sulfonic groups generally give higher chemical selectivity and enantioselectivity than those of the catalysts grafted via rigid phenyl sulfonic groups. When chiral Mn(salen) catalysts were...