Optically pure 2-(fluoromethyl)-2-[(4-methylphenylsulphinyl)methyl]oxirane has been obtained in good yield and with high d.e. by reacting diazomethane with optically pure 1-fluoro-3-(4-methylphenylsulphinyl)propan-2-one. Regio- and stereo-selective openings of oxirane ring performed with selected nucleophiles afforded several useful derivatives.
optically active sulphenyl and sulphonyl fluorohydrins were obtained by reduction of ketones with baker's yeast or by enzymatic resolution of their racemic esters using Candida cylindracea lipase. Crystallization of partially optically active fluorohydrins gave enantiomerically pure forms. Enantioselectivity of the enzymatic reactions is affected by steric requirements of the substituents.