Efficient methods for the synthesis of pyrido[2,3-d]pyrimidin-5-ones from 4-amino-5-acetylpyrimidines

New methods for annelation of a pyridine ring to a pyrimidine ring were suggested. Substituted 8H-pyrido[2,3-d]pyrimidin-5-ones (8a-f) were synthesized by the interaction of 2,6-disubstituted 4-amino-5-acetylpyrimidines (1–4) with formamide or acetamide acetals followed by cyclization under the action of sodium methoxide in methanol. 2,4-Disubstituted 7-phenyl-8H-pyrido[2,3-d]pyrimidin-5-ones (11a-c) were prepared by the reaction of 2,6-disubstituted 5-acetyl-4-benzoylaminopyrimidines (10a-c) with MeONa in boiling BuOH.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1469–1474, August, 1994.