Synthesis and applications of tetrahydro-2-pyridinones via aza-diels-alderreactions of thio-substituted 1,3-dienes with arylsulfonyl isocyanates

The first aza-Diels-Alder reactions of arylsulfonyl isocyanates with thio-s ubstituted 1,3-dienes via the 3-sulfolene precursors I gave the cyclized pr oducts 3 with complete control of chemo- and regioselectivity. The cyclized products 3a and 5 underwent further reactions with nucleophiles and bases to give useful heterocyclic compounds. The N-tosyl group of the cyclic prod ucts could be selectively replaced by hydrogen or another substituent.