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 2 a-c with phosphoryl chloride or thionyl chloride gave rise to the 7-substituted 2-chloroquinoline-3-carboxylic acids 3 a-c and 7-substituted 2-chloro-3-chlorocarbonylquinolines 5 a-c respectively. The 2-chloro function in compounds 3 a-c was replaced by 2-aminothiazole or 2-aminopyridine to give 2-(thiazol-2-yl)aminoquinoline-3-carboxylic acids 4 a-c or 2-(pyrid-2-yl)aminoquinoline-3-carboxylic acids 4 d-f. Treatment of 5 a-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 7 d-f were synthesized by heating 5 a-c with the heterocyclic amines in toluene or by heating 6 a-f under reflux in dimethylformamide. The products were evaluated in vitro for potential antimicrobial activity.