Synthesis and antibacterial activity of some novel fluorobenzothiazole derivatives

A series of 2,2'-(2-(2-benzylidenehydrazinyl)-6-fluorobenzo[d]thiazol-7-ylazanediyl) diethanol derivatives (4a-e) were synthesized in order to examine their in vitro antimicrobial activities against Staphylococcus aureus, Bacillus subtilis Gram-positive and Escherichia coli, Pseudomonas aeruginosa Gram-negative bacteria. 4-fluoro-3-chloroaniline was treated with potassium thiocyanate in presence of bromine in glacial acetic acid to get 2-amino-7-chloro-6- fluoro benzothiazole (1), which was further treated with hydrazine hydrate and concentrated HCl to get of 2-amino-7-chloro-6-fluoro-benzothiazole (2). Then Schiff’s base (3a-e) is prepared by reaction of fluoro-benzothiazole with different substituted aromatic aldehydes. The final targeted compounds (4a-e) were synthesized by substituting seventh chlorine of compound 3a-e by diethanolamine in presence of triethylamine. All the compounds were characterized by melting point, TLC and the chemical structures of the compounds were elucidated by IR, 1H NMR, mass spectroscopy. Among the series, compounds 4b, 4d and 4e exhibited good antibacterial activity profile as compared with the standard. In summary, preliminary results indicate that some of the newly synthesized title compounds exhibited promising antibacterial activities and they warrant more consideration as prospective antimicrobials.