Alkylidenephosphoranes in Heterocyclic Synthesis: Reactivity of Benzoxazinones with Resonance-Stabilized Phosphorus Ylides

2H-3,1-Benzoxazine-2,4(1H)-dione and its N-methyl analogue react with alkylidenephosphoranes to give substituted quinolines and benzazepines as well as indanone and furan derivatives. Reaction mechanisms to explain the formation of products obtained are outlined.