Preparation of enantiopure sultams by intramolecular Diels–Alder reaction of furan-containing vinylsulfonamides

Enantiomerically pure δ- and γ-sultams have been prepared by intramolecular [4+2] cycloaddition of N-1-phenylethyl substituted vinylsulfonamides with purely thermal activation and under high pressure. An optimized procedure for reductive debenzylation of the resultant δ-sultams is also reported.