Syntheses of arylsulfonyl-1,3,4-thiadiazoles

Synthesis and antibacterial activity of N-[5-chlorobenzylthio-1,3,4-thiadiazol-2-yl] piperazinyl quinolone derivatives

A series of N-[5-(chlorobenzylthio)-1,3,4-thiadiazol-2-yl] piperazinyl quinolone derivatives (4a-I) have been synthesized by reaction of piperazinyl quinolones with 5-chloro-2-(chlorobenzylthio)-1,3,4-thiadiazoles. Their structures were confirmed by elemental analysis, IR and NMR spectra. The antibacterial activities of 4a-I against a variety of Gram-positive and Gram-negative bacteria were determined. Several compounds showed a good antibacterial activity against Gram-positive bacteria among which, compound 4e with a 2-chlorobenzylthio moiety in ciprofloxacin derivative, exhibited high activities against Staphylococcus aureus and Staphylococcus epidermidis (MIC = 0.06 microg/mL). The structure-activity relationship (SAR) study revealed that the position of chlorine atom on benzyl moiety would dramatically affect the antibacterial activities of the synthesized compounds.

Synthesis and antibacterial activity of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl)piperazinyl quinolone derivatives

A series of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl) derivatives of piperazinyl quinolones was synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit high activity against Gram-positive bacteria; Staphylococcus aureus and Staphylococcus epidermidis, comparable or more potent than their parent N-piperazinyl quinolones norfloxacin and ciprofloxacin as reference drugs. The SAR of this series indicates that both the structure of the benzyl unit and the S or SO(2) linker dramatically impact antibacterial activity.