Mercuric oxide, hydrolysis dithianes

Oxidative hydrolysis of 2-aeyl-l -dithiane derivatives. A study of the hydrolysis of 2-acyl-1,3-dithianc derivatives by mercuric chloride (HgCl ) has been published. However, hydrolysis of 2-acyl-l,3-dithianes is slow. In this case use of N-haiosuccini-mide reagents is recommended. Either N-bromo uccinimide or N-chlorosuccinimidc-silver nitrate is suitable for oxidative hydrolysis of 1,3-dithiane derivatives. The N-halosuccinimide reagents are useful for hydrolysis of 2-acyl-1,3-dithianes to 1,2-dicarbonyl compounds. 

A synthesis of a,jS-unsaturated aldehydes has been effected by reaction of 2-lithio-l,3-dithiane with epoxides (equation 54). It was found that treatment of the dithianyl alcohol 59 with mercuric oxide-boron trifluoride caused dehydration and hydrolysis to give the tx, -unsaturated aldehyde 60 in good yield. Standard methods for removal of the thio-acetal function were not successful in these cases. 

---