Purines, pyrimidines, and imidazoles. Part XXIX. Some reactions of N-acetyl-N′-(β-ethoxyacryloyl)ureas leading to uracils, aminopyrazoles and pyrazolo[3,4-d]pyrimidines

Abstract

N-Acetyl-N′-cyanoacetylurea, prepared by acetylation of cyanoacetylurea with acetic anhydride and sulphuric acid, reacted with acetic anhydride and triethyl orthoformate to give N-acetyl-N′-(α-cyano-β-ethoxyacryloyl)urea. This, with primary aromatic or aliphatic amines, gave N-acetyl-N′-[α-cyano-β-aryl(or alkyl)aminoacryloyl]ureas, which were cyclised to 1-substituted 5-cyano-(or, under one set of basic conditions, 5-carbamoyl) uracils by the action of heat in pyridine solution or by treatment with alkali. Reaction of the ethoxyacryloylurea with phenyl-hydrazine gave N-acetyl-N′-(3-amino-2-phenylpyrazol-4-ylcarbonyl)urea, which was hydrolysed by alkali to N-(3-amino-2-phenylpyrazol-4-ylcarbonyl)urea. This was converted into 1-phenylpyrazolo[3,4-d]pyrimidine-4,6-dione when heated in pyridine. The last compound was an end-product of a similar series of reactions involving the reaction of phenylhydrazine with α-cyano-β-ethoxy-N-ethoxycarbonylacrylamide.