Synthesis of Some Novel Quinoline-3-carboxylic Acids and Pyrimidoquinoline Derivatives as Potential Antimicrobial Agents

Abstract

The synthesis and in vitro antimicrobial evaluation of several quinoline and pyrimidoquinoline derivatives are described. Treatment of 7‐substituted quinolin‐2(1H)‐one‐3‐carboxylic acids 2a—c with phosphoryl chloride or thionyl chloride gave rise to the 7‐substituted 2‐chloroquinoline‐3‐carboxylic acids 3a—c and 7‐substituted 2‐chloro‐3‐chlorocarbonylquinolines 5a—c respectively. The 2‐chloro function in compounds 3a—c was replaced by 2‐aminothiazole or 2‐aminopyridine to give 2‐(thiazol‐2‐yl)aminoquinoline‐3‐carboxylic acids 4a—c or 2‐(pyrid‐2‐yl)aminoquinoline‐3‐carboxylic acids 4d—f. Treatment of 5a—c with the same heterocyclic amines at room temperature furnished the corresponding 7‐substituted 2‐chloro‐3‐heteryl‐aminocarbonylquinolines 6a—f. The tetracyclic 9‐substituted thiazolo[3′, 2′:1, 2]‐pyrimido[4, 5‐b]quinolin‐5‐ones 7a—c and 10‐substituted pyrido[1′, 2′:1, 2]‐pyrimido[4, 5‐b]quinolin‐6‐ones 7d—f were synthesized by heating 5a—c with the heterocyclic amines in toluene or by heating 6a—f under reflux in dimethylformamide. The products were evaluated in vitro for potential antimicrobial activity.