Nucleophilic recyclization of pyrrole[5,1-c][1,4]benzoxazine-1,2,4-trione with simultaneous cleavage of the oxazine and pyrrole rings

o-Phenylenediamine (I) reacts with 1-alkyl-4-benzoyl-5-phenyl-2,3-dihydro-2,3-pyrrolediones initially adding to the nitrogen atom in position 5 and subsequently by attack of the carbonyl group of the benzoyl fragment and closure of the diazepine ring [1]. 3-Benzoyl-l,2,4,5-tetrahydropyrrolo[1,5-a]quinoxaline-l,2,4-trione behaves similarly, the 2,3-pyrroledione ring being included in a condensed heterocycle system. In the reaction of 3-benzoyl-1,2-dihydro-4H-pyrrolo[5, I-c][ 1,4]benzoxazine1,2,4-trione (II) with compound I we have isolated the o-hydroxyanilide of 3-(2-oxo-1,2,3,4-tetrahydro-3-quinoxalinylidene)benzoylpyruvic acid (III). Heating compound III with benzylamine leads to aminolysis of the oxamide fragment and the formation of N-benzylN'-o-hydroxyphenyloxamide (V) and the known 3-phenacylidene-l,2,3,4-tetrahydro-2-quinoxalone (IV): o%___~o % o .