In situ-generated chiral iron complex as efficient catalyst for enantioselective sulfoxidation using aqueous H2O2 as oxidant

Abstract

A series of amino alcohol-derived, Schiff-base ligands L1–L4 were synthesised and characterized. Iron complexes of these ligands [FeL1(acac)], [FeL2(acac)], [FeL3(acac)] and [FeL4(acac)] were generated in situ to catalyze the asymmetric oxidation of prochiral sulfides using aqueous H₂O₂ as a terminal oxidant. One of these complexes [FeL1(acac)] was identified as a very efficient catalyst for the enantioselective oxidation of a series of alkyl aryl sulfides with excellent enantioselectivity (75–96% ee), conversion (up to 92%) and chemo selectivity (up to 98%). During the optimization process, a series of electron-donating benzoic acid derivatives were found to favour both conversion and enantioselectivity.