Thermal and high pressure intramolecular Diels-Alder reaction of vinylsulfonamides.

Vinylsulfonamides with a furan, carbocyclic, semicyclic or acyclic 1,3-diene moiety are synthetized via a domino elimination-amidation reaction of 2-chloroethanesulfonyl chloride. Intramolecular Diels-Alder reaction of these vinylsulfonamides with thermal (toluene, 110 degrees C) or high pressure (dichloromethane, 13 kbar) activation provides efficient access to a range of gamma- and delta-sultams following a 2-3 d long synthetic procedure. Enantiopure sultams are readily obtained from N-1-phenylethyl substituted vinylsulfonamides.