Synthesis of Angular [1,2,5]Oxadiazolo[3,4-b]pyrazino-[1',2':1,2]pyrrolo[2,3-e][1,4]diazepine by Stepwise Reaction of Pyrrolo[1,2-a]pyrazinetrione with 3,4-Diaminofurazan

Diaminofurazan reacted with 8-benzoyl-2-phenyl-3,4-dihydropyrrolo[1,2-a]pyrazine-1,6,7(2H)- trione to give addition product of the amino group to the double bond of the pyrrole ring, which underwent cyclization to 2,8-diphenyl-3,4-dihydro[1,2,5]oxadiazolo[3,4-b]pyrazino[1',2': 1,2]pyrrolo[2,3-e][1,4]diazepine-1,6,7(2H,9H,13H)-trione by the action of N,N'-dicyclohexylcarbodiimide.