Remarkably efficient and direct route to quinolines and benzoazepines from the condensation of benzoxazinediones with phosphonium carbanion salts

Treatment of 2H-3,1-benzoxazine-2,4(1H)-dione (1a) with vinyltriphenyl-phosphonium bromide (2a) gives substituted benzoazepine 8a (48% yield) and indolizinone 12 (27% yield), whereas substituted quinolinone 15 and benzoazepine 8b were isolated from the reaction of N-methylisatoic anhydride (1b) and 2a. Furthermore, a series of quinoline derivatives was synthesized from the reactions of la and 1b with allyl-(2b), alkyl-(2c), (2d), and cyanomethyl-(3) triphenylphosphonium salts.