Aza-Diels–Alder reactions and synthetic applications of thio-substituted 1,3-dienes with arylsulfonyl isocyanates

The first aza-Diels–Alder reactions of arylsulfonyl isocyanates with thio-substituted 1,3-dienes via the 3-sulfolene precursors 1 gave the cyclized products 3 with complete control of regio- and chemoselectivity. The cyclized products 3a and 4 underwent further interesting reactions with nucleophiles and bases to give useful heterocyclic compounds.