4.5- Diphenyl-l ,3,2-dioxathiolane 2-oxide

Interestingly, thermal decomposition of 4,5-diphenyl-l,3,2-dioxathiolane 2-oxide depends on the stereochemistry of the starting diols. For example, the cyclic sulfite derived from meso-hydrobenzoin (66a) decomposed on heating to give a good yield of desoxybenzoin (67), while the trans isomer 66b (derived from if/-hydrobenzoin) furnished diphenylacetaldehyde (68) quantitatively [Eqs. (16) and (17)]. 

Photolysis of meso- and d/-4,5-diphenyl-l,3,2-dioxathiolane 2-oxide also furnished similar products. The formation of different products is rationalized in term of the pathways shown in Scheme 16. 

---