Catalytic enantioselective epoxidation of olefins by chiral mono-faced strapped porphyrin with nitrogen blocking ligand

Abstract

The chiral mono-faced binaphthyl strapped porphyrins were synthesized and1H NMR characterized. Asymmetric epoxidation of olefins such as styrene derivatives and trimethylsilyl ethylene with iodosobenzene as oxidant was achieved by using the iron complex as catalyst in the presence of a nitrogen ligand. Enantiomeric excess (ee) of 80% and yield of 88% were measured for the epoxidation of styrene in the presence of 4-phenyl pyridine. The coordination capability of nitrogen ligands to catalysts measured by UV-vis spectrophotometric titrations evidence that the unstrapped face of the mono-faced catalyst is blocked by the nitrogen ligand coordination to the iron ion of the catalyst.