Dithio acetals and ketals

Dithiasuccinimides, to protect amines, 359 4H, 7//-1,3-Dithiepin derivatives, to protect carbonyl groups, 207 Dithio acetals and ketals to protect carbonyl groups, 7, 157,... 

Carbonyl functions often are protected as thioacetals, because these derivatives are stable to acids and bases. Dithio-acetals and -ketals generally are prepared by reaction of the carbonyl compound with a thiol in the presence of an acid catalyst. This transformation has been used in carbohydrate chemistry for a long time to lock aldoses in their acyclic forms (see equation 26). In recent years, this blocking principle for carbohydrates has been exploited in several chiral pool syntheses. Several other methods for... 

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