Surface Confined O=MnV (Salen)Oxene Catalyst and High Turnover Values in Asymmetric Epoxidation of Unfuctionalized Olefins

Given the widespread importance of chiral epoxides in chemical, biochemical and agricultural fields, anefficient synthesis that avoids wasteful use of the catalyst and assures its total recovery and reuse andhigh turnover values is highly desirable. We report on a thermally and temporally robust covalentmonolayer of (salen)Mn(III) molecules on silica functionalized substrates that resulted in an activeheterogeneous catalyst for enantioselective epoxidation of 6-ciano-2,2-dimethyl-chromene, chosen as amodel alkene, in high yields and high turnover numbers. No catalyst leaching was observed thusallowing continuous recycling. Experimental XPS evidence for the formation of the surface confinedO]MnV(salen) oxene species has been obtained.