Asymmetric Oxidation of 1,3-dithiolanes - A Route To the Optical Resolution of Carbonyl-compounds

The asymmetric oxidation (-BuO2H, Ti(OPr-)4, DET) of a series of 1,3-dithiolanes was carried out to produce the corresponding S-oxides with high chemical and optical yields. By contrast, the oxidation of 1,3-dithianes and 1,3-oxathiolane prepared from the same carbonyl compounds gave much lower optical yields. The optical resolution of the model ketone, dl-menthone, a) 1,3-dithiolane formation b) asymmetric S-oxidation c) chromatographic diasteromeric separation d) regeneration of the carbonyl group, (93% optical yield), is described.