Cleavage dithiane protecting group

McHale, W.A. and Kutateladze, A.G. (1998) An efficient photo-SET-induced cleavage of dithiane-carbonyl adducts and its relevance to the development of photoremovable protecting groups for ketones and aldehydes. Journal of Organic Chemistry, 63, 9924—9931. 

In this section, the protections and cleavages of four protecting groups for aldehydes and ketones are presented dimethylketal 1,3-dioxane 1,3-dioxolanc and 1,3-dithiane. 

A carbonyl group can be protected as a sulfur derivative—for example, a dithio acetal or ketal, 1,3-dithiane, or 1,3-dithiolane—by reaction of the carbonyl compound in the presence of an acid catalyst with a thiol or dithiol. The derivatives are in general cleaved by reaction with Hg(II) salts or oxidation acidic hydrolysis is unsatisfactory. The acyclic derivatives are formed and hydrolyzed much more readily than their cyclic counterparts. Representative examples of formation and cleavage are shown below. 

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