Synthesis of ribonucleosides of 2-thioxopyrido [2,3-d]pyrimidines by phase transfer catalysis and their antimicrobial activity

The ribonucleosides viz; 2-thioxo-3,5,7-trisubstituted-1-(2,3,5-tri-O-benzoyl-beta -D-ribofuranosyl)pyrido[2,3-d]pyrimidine-4 (1H)-ones have been synthesized via phase transfer ribosylation of 2-thioxo- 3,5,7-trisubstituted pyrido[2,3-d]pyrimidine-4(IH)-ones with 2,3,5-tri-O-benzoyl-beta -D- ribofuranosyl bromide in biphasic solvent such as CH2Cl2-50% aqueous NaOH using tetrabutylammonium bromide as phase transfer catalysis (PTC). The synthesized compounds have been characterized by elemental analyses, spectral data and screened for their antimicrobial activity.