Synthesis of Spiro(pyrrol-2,5'-pyrrolo[2,3-d]pyrimidine)-2',4',5,6'-tetraones by the Reaction of Pyrrolo[2,1-c][1,4]oxazinetriones with 6-Aminopyrimidine-2,4-diones

8-Aroyl-3,4-dihydro-1 H -pyrrolo[2,1- c ][1,4]oxazine-1,6,7-triones react with 6-aminopyrimidine-2,4(1 H ,3 H )-diones to form 3-aroyl-4-hydroxy-1-(2-hydroxyalkyl)spiro(pyrrole-2,5'-pyrrolo[2,3- d ]pyrimidine)-2',4',5,6'(1 H ,1' H ,3' H ,7' H )-tetraones. The structure of the products was confirmed by X-ray diffraction analysis.