A simple one-pot synthesis of Jacobson–Katsuki type chiral Mn(III)–salen catalyst immobilized in silica by sol–gel process and applications in asymmetric epoxidation of alkenes

Salen ligand synthesized from (1R,2R)-(-)-1,2-diaminocyclohexane and 2-hydroxy-3(3-triethoxysilyl-propyl)-benzaldehyde has been used as manganese chelate for the immobilization of the catalytic site. Sol–gel hydrolysis and polycondensation of this chelate with ten equivalents of tetraethyl orthosilicate produced the heterogeneous catalyst. This catalyst is active in enantioselective epoxidations of alkenes in 61–76% yield and 54–86% e.e., using sodium hypochlorite as the primary oxidant. Additionally the immobilized catalyst shows an improvement in the enantioselectivity when compared to the homogeneous Mn(III)–salen analog.