Microwave-irradiated synthesis and antimicrobial activity of 2-phenyl-7-substitutedalkyl/arylaminoquinoline-4-carboxylic acid derivatives

Abstract

This report focuses on the synthesis of 2-phenyl-7-substitutedquinoline-4-carboxylic acid derivatives through both conventional and microwave-irradiated methods. Intermediate 7-chloro-2-phenyl-quinoline-4-carboxylic acid was synthesized by condensation and cyclization of benzaldehyde, pyruvic acid, and m-chloroaniline in the presence of absolute ethanol and further substituted with aromatic, aliphatic, and alicyclic amines to obtain the desired 2-phenyl-7-substitutedaryl/alkylamino-quinoline-4-carboxylic acid derivatives under the influence of microwave irradiation, with output power ranging from 160 to 480 W, yield ranging from 90% to 95%, and a shorter reaction time than with the conventional method. All the synthesized compounds were screened for in vitro antimicrobial activity against six gram-positive and four gram-negative organisms. All synthesized compounds are active against a broad spectrum of microorganisms, with prominent results for Streptococcus pyrogenes and Pseudomonas aeruginosa. Compounds 7c and 7h showed a minimum inhibitory concentration of less than 10 μg.