Vk. Aggarwal et al., STEREOSELECTIVE EPOXIDATION OF BIS-SULFINYL ALKENES AND APPLICATION TO THE ASYMMETRIC-SYNTHESIS OF ALPHA-SUBSTITUTED CARBOXYLIC-ACIDS, Phosphorus, sulfur and silicon and the related elements, 120, 1997, pp. 351-352
Ketene thioacetals 3 can be easily prepared in optically pure form and
react diastereoselectively with metal peroxides, The resulting bis-su
lfinyl oxiranes can be converted in a single step to alpha-substituted
acids.