A praedcal opthesis of trans-3,4-aiol derivatives of subnituted chromans via epoxidation with combined use of mangenese (III) salen complex 3 and hydrgen perokide has been developed. These diol derivatives are key intermediates for the syntheis of a series of biologicallimportant chroman compounds. A praedcal opthesis of trans-3,4-aiol derivatives of subnituted chromans via epoxidation with combined use of mangenese (III) salen complex 3 and hydrgen perokide has been developed. These diol derivatives are key intermediates for the syntheis of a series of biological lipids chroman compounds.