Synthesis and antimicrobial evaluation of some new pyrido[2,3-<i>d</i>]pyrimidines and their ribofuranosides

430-4324-Amino-5, 7-disubstituted -pyrido[2, 3-d]pyrimidin-2(1H)ones 3 and 5, 7-disubstituted-pyrido[2, 3-d]-pyrimidine-2, 4-(1H, 2H) dithiones 4 have been synthesized by the condensation of 2- amino-3-cyano-4, 6-disubstituted-pyridines 2 with urea and carbon disulphide, respectively. Compounds 2 have been synthesized by condensing chalcones 1 with malononitrile and ammonium acetate. The condensation of trimethylsilyl derivatives of compounds 3 with β-D-ribofuranose 1-acetate-2, 3, 5-tribenzoate in the presence of SnCl4 furnish the nucleosides, viz, 4-amino-5, 7- disubstituted-1-(2, 3, 5-tri-O-benzoyl-α-D-ribofuranosyl)pyrido[2,3-d] pyrimidin-2(1H)-ones 5. Compounds 3-5 have been screened for their antibacterial and antifungal activities