تحضيرتترازولات ثنائية التعويض في الموقعين 5،1 و دراسة فعاليتها ضد البكتريا

Synthesis of 1,5-Disubstituted Tetrazoles and Study of Their Antibacterial Activity

     In this work two series of new 1,5-disubstituted tetrazole derivatives containing azo group and benzothiazole moiety have been synthesized. At first, the primary aromatic amine 2-aminobenzothiazole was converted to the corresponding azoaldehyde derivative containing benzothiazole moiety 1a via coupling reaction of its diazonium salt with 2-hydroxy benzaldehyde, which dissolved in sodium hydroxide solution, as coupling reagent. Next, the resulting azoaldehyde 1a was respectively introduced in acid-catalyzed condensation reactions with the primary aromatic amines (3- bromoaniline, 2-chloroaniline, 2,4-dichloroaniline, 4-nitroaniline, 3-nitro aniline, 2-amino-5-mercapto-1,3,4-thiadiazole and 2-aminobenzothiazole) in absolute ethanol to give seven azoimines containing benzothiazole moiety 2a-g respectively. Later, the synthesized azoimines 2a-g were respectively introduced in [3+2] cycloaddition reactions with sodium azide in tetrahydrofuran to obtain seven new 1,5-disubstituted tetrazole derivatives 3a-g.

Then, azoaldehyde derivatives 1a`-e` were prepared through coupling reactions of the diazonium salts for the primary aromatic amines (3-bromo aniline, 2-chloroaniline, 2,4-dichloroaniline, 4-nitroaniline and 3-nitro aniline) with 2-hydroxybenzaldehyde, which dissolved in sodium hydroxide solution, as coupling reagent. Next, the resulting azoaldehydes

1a`-e` were introduced in acid-catalyzed condensation reactions with 2- aminobenzothiazole in absolute ethanol to obtain five azoimines containing benzothiazole moiety 2a`-e` respectively. Later, treatment of the resulting azoimines 2a`-e` with sodium azide under the same cycloaddition [3+2] reaction conditions afforded five new 1,5-disubstituted tetrazole derivatives 3a`-e` respectively.

The structures of all new synthesized tetrazoles have been confirmed by the spectroscopic means including FT-IR, 1H NMR and Mass. All new synthesized tetrazoles have been tested for their antibacterial activity against two types of bacteria, Staphylococcus aureous (Gram-positive) and Escherichia coli (Gram-negative). The results indicated that all synthesized tetrazoles except compound 3d showed medium-high activity against Gram-positive bacteria. On the other hand, all tetrazoles showed no effect against Gram-negative bacteria.