Syntheses and Properties of Some Pyrrolo [2, 3-d] pyrimidine Derivatives

The reaction of 6-amino-1, 3-dimethyluracil (I) with phenacyl bromide in DMF gave 1, 3-dimethyl-6-phenylpyrrolo [2, 3-d] pyrimidine-2, 4 (1H, 3H)-dione (II) in high yield. The reaction of I and phenacyl bromide in acetic acid afforded the isomeric 1, 3-dimethy1-5-phenylpyrrolo [2, 3-d] pyrimidine-2, 4 (1H, 3H)-dione as a byproduct besides II. Nitrosation of II gave 1, 3-dimethy1-5-nitroso-6-phenylpyrrolo [2, 3-d] pyrimidine-2, 4 (1H, 3H)-dione (III) along with the corresponding 5-nitro derivative. Ring expansion of III by the Beckmann rearrangement was carried out to give 1, 3-dimethy 1-5-hydroxy-6-phenylpyrimido [4, 5-d]-pyrimidine-2, 4 (1H, 3H)-dione. Denitrosation of III by the action of sulfuric acid was observed.