Syntheses , Characterization and Biological Activity of Some 1 , 2 , 4-Triazole Derivatives

Syntheses of a series of 3-alkyl-4amino-5cyanomethyl-4H-1, 2, 4triazoles with active methylene groups are described. The newly synthesized compounds were characterized by spectral and elemental analyses. Some compounds were screened for their antibacterial activity against S. aureus, E. coli, B. subtilis and P. aeruginosa. All the compounds carrying 1, 2, 4triazole moiety showed significant biological activity.


Introduction
The chemistry of heterocyclic compounds continuous to be an explore field in the organic chemistry.The importance of triazole derivative lies in the field that these have occupied a unique position in heterocyclic chemistry due to their antimicrobial activity 1-3 .3-Alkyl-5-cyanomethyl-4H-1, 2, 4-triazole derivatives have been obtained by treating alkylimidate hydrochlorides and ester ethoxycarbonyl hydrazones with cyanoacetic acid hydrazide 4 .It was reported that tert-butylcarbazates can be hydrolyzed in acidic solutions to give hydrazinium salts 5,6 .Indeed, some 3, 5-dialkyl-4-tert-butoxycarbonylamino-4H-1,2,4triazole derivatives have also been hydrolyzed to their corresponding salts by treatment with 6 N HCl.These hydrochlorides could be converted to 3,5-dialkyl-4-amino-4H-1,2,4-triazoles by using equivalent amounts of ethoxide anion or ethanol 7 .In views of these observations and in continuation of our earlier work [8][9][10] on the syntheses of some 1, 2, 4-& 1, 2, 3-triazole derivatives, we now report the syntheses of some more triazole derivatives derived from ethyl carboxylate tert-butoxycarbonyl hydrazones and their biological activities.

Experimental
Melting and boiling points were determined on a Gallen Kamp apparatus in open capillaries and are uncorrected.IR spectra (KBr in cm -1 ) were recorded on a Jasco FT -IR 5300 spectrophotometer and PMR spectra (DMSO-d6) on an EM 390 spectrometer using TMS as an internal standard (chemical shift in δ ppm).Purity of the compounds was checked by TLC using silica gel G.All compounds showed satisfactory elemental analyses.

Biological activity
The antibacterial activity of twelve compounds was studied by employing filter paper disc method [12][13][14][15] .Representative organisms selected for evaluation of antibacterial activity were S. aureus, E. coli, B. subtilis and P. aeruginosa.The antibacterial activity of each compound was evaluated at 100 µg mL -1 and 10 µg mL -1 concentrations.The compounds were tested as a solution or suspension in DMF.An important and useful drug ampicillin was also tested under similar conditions, with view to compare the results.
Ampicillin is a beta-lactum antibiotic 16 that has been used extensively to treat bacterial infections since 1961.Ampicillin is designated chemically as (2S, 5R, 6R Ampicillin is able to penetrate gram-positive and some gram-negative bacteria 17 .Ampicillin acts as a competitive inhibitor of enzyme transpeptidase.As a powder ampicillin is white with slight yellow cast and is soluble in water.Ampicillin is often used as a selective agent in molecular biology to confirm the uptake of genes by bacteria.Ampicillin applied for the treatment of pneumonia patients, bronhopnevmonijami with abscesses light, angina, peritonitis, cholecystitis, sepsis, intestinal infections and postoperative infection in the soft tissue and other infections caused by susceptible to the microorganism 18 . The results indicate that all these compounds showed moderate to strong activity (Table 1).Compounds 2a, 2c, 2d, 3a, 3d, 4a and 4d showed very good activity against S. aureus, E. coli, B. subtilis and P. aeruginosa.Similarly, compounds 2b, 3b, 3c, 4b, and 4c showed moderate to mild activity against all four bacteria.From the above observation it is clear that the 1, 2, 4triazole derivatives are more active and play a prominent role in the biological activity.

Results and Discussion
In the present work, compound ethyl carboxylate tert-butoxycarbonyl hydrazone(1) required as starting material was obtain in one-pot reaction by heating alkylimidate hydrochlorides and tert-butylcarbzate at 120 0 C for the period of 3.

Conclusion
In conclusion, a group of 1, 2, 4-triazole derivatives incorporating active methylene groups were synthesized and characterized.All these compounds containing 1, 2, 4-triazole moiety (3) is more active and plays a prominent role in biological activity.The structure of all the compounds are confirmed by IR, PMR & MS spectral data, and are further supported by correct elemental analysis (experimental part).

Table 1 .
Evaluation of antibacterial activity of the compounds.