Microwave‐assisted synthesis of quinolone derivatives and related compounds

Abstract magnified image The Gould‐Jacob type of reaction for the synthesis of ethyl 5‐ethyl‐8‐oxo‐5,8‐dihydro‐[1,3]‐dioxolo[4,5‐g]quinoline‐7‐carboxylate 4 has been carried out conventionally by the condensation between N ‐ethyl‐3,4‐methylenedioxyaniline 1 and diethyl ethoxymethylenemalonate 2 gave the unsaturated ester 3 and thermal cyclization in refluxing diphenyl oxide gave quinolone ethyl ester 4 and the results obtained were compared with single step microwave irradiation under solvent free conditions for the synthesis of 4 . The esters on basic hydrolysis formed free acid 5 , which, upon treatment with thionyl chloride gave the acid chloride 6 . Treatment of acid chloride with o ‐phenylenediamine, hydrazine hydrate, ammonia, urea, and thiourea gave the amides ( 7 , 8 , 9 , 10 , 11 ). CS 2 treatment in presence of KOH on 8 gave 12 . We prepared 7 , 8 , 9 , 10 , 11 , 12 derivatives by conventional as well as microwave irradiation. These compounds have been characterized on the basis of IR, 1 H NMR, MS, and elemental analysis. All the compounds prepared herein were screened for their antibacterial activity. Compounds 4 , 5 possess promising antibacterial activity and compound 8 showed significant antibacterial activity. J. Heterocyclic Chem., (2010).