Synthesis and antibacterial activity of certain quinoline and quinazoline derivatives containing sulfide and sulfone moieties

Some aryl and/or heterocyclic mercaptans were allowed to react with 8-quinolyl chloroacetate (II), 8-quinolinoxyacetyl chloride (IV) and 3-(2′-chloroethyl)-2-methyl-3,4-dihydroquinazolin-4-one (X) in dry benzene and/or sodium hydroxide in absolute ethanol to give corresponding 8-quinolyl-α-mercaptoacetate (V), 8-quinolinoxythioacetate (VI) and 3-(2′-arylmercaptoethyl)-2-methyl-4-(3H)quinazolin-4-ones or 3-(2′-heterocyclicmercaptoethyl)-2-methyl-4(3H)-quinazolin-4-ones (XIa-h). The mercaptans V and XI were subjected to oxidation with hydrogen peroxide/acetic acid mixture (1:2) to afford the corresponding sulfones VII and XII. The structures of the synthesized compounds were elucidated by spectroscopic (IR and 1H-NMR) and elemental analyses. Some of these compounds were tested for their antimicrobial activities in comparison with tetracycline as a reference compound.