Olefin epoxidation by a (salen)Mn(III) catalyst covalently grafted on glass beads

The asymmetric epoxidation of unfunctionalized prochiral olefins catalyzed by chiral (salen)Mn(III)complexes is an important viable route to obtain chiral epoxides. Recently we proposed a monolayer of(salen)Mn(III) molecules on functionalized flat silica substrates as an active heterogeneous catalyst forenantioselective epoxidation of 6-cyano-2,2-dimethylchromene with huge turnover values. In the presentstudy we synthesized a monolayer of modified (salen)Mn(III) molecules on previously functionalized glassbead substrates in order to increase the active surface area. The catalyst activity of this system was testedwith different olefins and in some cases we observed enantioselectivity higher than in solution. The systemwas reused up to seven times with no variation in performance.