Design, synthesis and antimicrobial activities of 1-(4-oxo-3-(4-fluorophenyl)-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazide derivatives

Abstract

A new series of 1-(4-oxo-3-(4-fluorophenyl)-3H-quinazolin-2-yl)-4-(substituted) thiosemicarbazides (AR1-AR10) were obtained by the reaction of 2-hydrazino-3-(4-fluorophenyl) quinazolin-4(3H)-one (6) with different dithiocarbamic acid methyl ester derivatives. The key intermediate 3-(4-fluorophenyl)-2-thioxo-2,3-dihydro-1H-quinazolin-4-one (4) was obtained by reacting 4-fluoroaniline (1) with carbon disulphide and sodium hydroxide in dimethyl sulphoxide to give sodium dithiocarbamate, which was methylated with dimethyl sulfate to yield the dithiocarbamic acid methyl ester (2) and condensed with methyl anthranilate (3) in ethanol yielded the desired compound (4) via the thiourea intermediate. The SH group of compound (4) was methylated for the favorable nucleophilic displacement reaction with hydrazine hydrate, which afford 2-hydrazino-3-(4-fluorophenyl)-3H-quinazolin-4-one (6). All synthesized compounds (AR1-AR10) were also screened for their antimicrobial activity against selective gram positive and gram negative by agar dilution method. In the present study compounds AR8 and AR9 were emerged as the most active compounds of the series.