Ketene dithioacetals in the aza-Diels-Alder reaction with N-arylimines: a versatile approach to tetrahydroquinolines, 2,3-dihydro-4-quinolones,and 4-quinolones

reaction: see text] The first successful use of ketene dithioacetals as dienophiles in the aza-Diels-Alder reaction with N-arylimines is described. Among the ketene dithioacetals tested, 1,4-benzodithiafulvenes are most effective in assembling the tetrahydroquinoline core. Subsequent chemical manipulations provide a concise and divergent approach to the synthesis of 2,3-tetrahydroquinolines, 2,3-dihydro-4-quinolones, and 4-quinolones.