CATALYTIC AND ASYMMETRIC EPOXIDATION OF UNFUNCTIONALIZED ALKENES WITH HYDROGEN-PEROXIDE AND (SALEN)MN(III) COMPLEXES

Catalytic epoxidation of two unfunctionalized alkenes, 1,2-dihydronaphthalene and trans-beta-methylstyrene, is reported using achiral and chiral (Salen)Mn(III) complexes 1-3 together with a nitrogen heterocycle as axial ligand in the presence of 30% aqueous hydrogen peroxide as oxidant. Typically, the reaction system consisted of the substrate, oxidant, ligand, and salen in a ratio of 1:2-3.5:0.4:0.025-0.05. The best ligands were imidazole and N-methyl imidazole. The highest ee-values obtained were 60% for 1,2-dihydronaphthalene oxide and 47% for trans-beta-methylstyrene oxide.