α,β-Unsaturated 1,3-oxathiolanes as masked heterodienes in the thio Diels–Alder reaction with styrene derivatives

The cycloaddition reactions of various alkyl and aryl substituted α,β-unsaturated 1,3-oxathiolanes with styrene derivatives led to dihydrothiapyrans in the presence of TiCl4. Some mechanistic aspects of the cycloaddition are presented.