Cinchona Alkaloid Supported In Mesoporous Silica

Nowadays,much intensive interest was focused on how to get high enantio-selective product in asymmetric catalytic processes.Confinement effect was one of the most usefull methods that enhance chiral induction and enantio-selectivity.In our work,we changed the pore sizes of the nanoporous supports and introduce cinchona alkaloid in the nanopores.²⁹Si NMR,¹³C NMR andα_s-plot analysis showed that the cinchona alkaloid was supported in the nanopores. Catalytic performance was evaluated by the asymmetric Friedel-Crafts reaction of indoles to imines,asymmetric 1,4-addition of Nitromethane to trans-Chalcone and Malonates to trans-Phenyl Nitroalkene.1.In the reaction of Nitromethane to trans-Chalcone,the enantio-selectivity of the product was improved with decreasing pore size.The heterogeneous catalyst with a pore size of 4.4 nm gave the best ee value,up to 93%.2.In the reaction of Malonates to trans-Phenyl Nitroalkene,when the pore size of the heterogeneous catalyst was less than 7.1 nm,the enantio-selectivity of the product increased to 98%. 3.In the reaction of indoles to imines,all heterogeneous catalyst showed good confinement effect.The enantio-selective of the product was similar to observed for the homogeneous catalyst,up to 98%.