Photochemically catalyzed Diels–Alder reaction of arylimines with N-vinylpyrrolidinone and N-vinylcarbazole by 2,4,6-triphenylpyrylium salt: synthesis of 4-heterocycle-substituted tetrahydroquinoline derivatives

Photochemically promoted Diels–Alder reactions of N-arylimines with N-vinylpyrrolidinone and N-vinylcarbazole were achieved by using 2,4,6-triphenylpyrylium tetrafluoroborate as a catalyst to produce corresponding 2-oxopyrrolidin-1-yl and carbazol-9-yltetrahydroquinolines in high yields.