Synthesis and Antimicrobial Evaluation of Some Novel Pyrido[2,3‐d] Pyrimidine Derivatives and Their Ribofuranosides

Abstract

2‐Amino‐3‐cyano‐4,6‐disubstituted pyridines 2a–c on treatment with arylisocyanate and arylisothiocyanate afforded 4‐imino‐3,5,7‐trisubstituted pyrido[2,3‐d] pyrimidin‐2(1H)‐ones 3a–c and 4‐imino‐3,5,7‐trisubstituted pyrido[2,3‐d]pyrimidin‐2(1H)‐thiones 4a–c, respectively. The ribofuranosides, namely, 4‐imino‐3,5,7‐trisubstituted‐1‐(2′,3′,5′‐tri‐O‐benzoyl‐β‐d‐ribofuranosyl) pyrido[2,3‐d]pyrimidin‐2(1H)‐ones 7a–c and 4‐imino‐3,5,7‐trisubstituted‐1‐(2′,3′,5′‐tri‐O‐benzoyl‐β‐D‐ribofuranosyl) pyrido[2,3‐d]pyri‐midin‐2(1H)‐thiones 8a–c, were synthesized by the condensation of trimethylsilyl derivatives of 3a–c and 4a–c with β‐d‐ribofuranosyl‐1‐acetate‐2,3,5‐tribenzoate. The structure of newly synthesized ribofuranosides and their precursors were established by elemental analyses, IR, 1H NMR and 13C NMR spectroscopy. All the synthesized compounds were screened for their antibacterial and antifungal activities against Escherichia coli, Staphylococcus aureus, Aspergillus niger, and Aspergillus flavus.

Synthesis and mycobacterial evaluation of 5‐substituted‐6‐acetyl‐2‐amino‐7‐methyl‐5,8‐dihydropyrido‐[2,3‐d]pyrimidin‐4(3H)‐one derivatives

“…2‐Substituted pyrido[2,3‐ d ]pyrimidin‐4(1 H )‐one derivatives showed activity against Gram‐positive ( B. subtilis , S. aureus ) and Gram‐negative bacteria ( E. coli and Klebseilla pneumoniae ) . 4‐Imino‐3,5,7‐trisubstituted pyrido[2,3‐ d ]pyrimidin‐2(1 H )‐ones and their ribofuranosides exhibited activity against E. coli and S. aureus …”