Iron-catalyzed epoxidation of olefins using hydrogen peroxide†

90 A practical method of olefin epoxidation was developed by combining FeCl3·6H2O and 1methylimidazole in acetone using H2O2 as the terminal oxidant. This system showed very good reactivity toward epoxidation of both terminal and substituted alkenes. The use of tridentate and tetradentate amine-bis(phenolate) ligands as additives was also examined. Modest improvement in selectivity was achieved if a bulky tridentate ligand was used. Generally, however, the simple catalyst system involving ferric chloride, 1-methylimidazole and dilute H2O2 in acetone proved most successful in achieving good to excellent yields of epoxide products for a number of substrates, including aromatic and aliphatic alkenes.