Chemistry of acyl(imidoyl)ketenes:: IX.: Synthesis and thermolysis of 3-aroyl-8-chloro-1,2-dihydro-4H-pyrrolo [2,1-c][1,4] benzoxazine-1,2,4-triones

Reactions of 3-Z-aroylmethylene-6-chloro-3,4-dihydro-2H-1,4-benzoxazine-2-ones with oxalyl chloride afford 3-aroyl-8-chloro-1,2-dihydro-4H-pyrrolo[2,1-c][1.4]benzoxazine-1,2,4-triones and Z-3-(2-aryl-2-chlorovinyl)-6-chloro-2H-1,4-benzoxazine-2-ones. Aroyl(imidoyl)ketenes generated by decarbonylation of pyrrolobenzoxazinetriones undergo dimerization through [4+2]-cycloaddition to form 4-aroyl-3)-aroyloxy-2-(2-oxo-2H-1,4-benzoxazin-3-yl)-1H,5H-pyrido[2,1-c] [ 1,4]benzoxazine-1,5-diones.