Synthesis of 8-aroylpyrrolo[1,2-a]pyrazine-1,6,7(2H)-triones and their reaction with water. New analogs of cyclic dipeptides

2-Aryl-8-aroyl-3,4-dihydropyrrolo[1,2-a]pyrazine-1,6,7(2H)-triones prepared from (Z)-1-aryl-3-(2-aryl-2-oxoethylidene)piperazin-2-ones and oxalyl chloride react with water to afford (E)-8D degrees-hydroxy-2-aryl-8-[aryl(hydroxy)methylene]tetrahydropyrrolo[1,2-a]pyrazine-1,6,7(2H)-triones. The crystal and molecular structure of 8-benzoyl-2-phenyl-3,4-dihydropyrrolo[1,2-a]pyrazine-1,6,7(2H)-trione and (E)-8D degrees-hydroxy-8-[hydroxy(phenyl)methylene]-2-phenyltetrahydropyrrolo[1,2-a]pyrazine-1,6,7(2H)-trione were studied by X-ray diffraction analysis.