A brief survey of the use of the Pummerer rearrangement for the alkylation of 1,3-oxathiolan-5-ones and 1,3-thiazolidin-4-ones

Oxidation of 1,3-oxathiolan-5-ones (1) gives acceptable yields of sulfoxides only when C4 is unsubstituted. Sulfoxides derived from 1,3-thiazolidine-4-ones (8) are easily prepared. Acid-catalyzed rearrangement in the presence of 1-alkenes or benzene leads to alkylation (arylation) at C5. Alkylation of 8c may be generally more effective than that of 1. An aldol condensation of 8c shows little stereoselectivity.