Background:
The aim of this study is to synthesize new Mannich bases and conazol derivatives with biological
activity by the microwave-assisted method.
Introduction:
1,2,4-Triazole-3-one (3) acquired from tryptamine was transformed to the corresponding carbox(thio)amides
(6a-c) via several steps. Compounds, 6a-c, were refluxed with sodium hydroxide to yield 1,2,4-triazole derivatives (7a-c).
Compounds 3 and 7a-c on treatment with different heterocyclic secondary amines in an ambiance with formaldehyde
afforded the Mannich bases 8-15 having diverse pharmacophore units with biologically active sites. The reaction of
compound 3 and 2-bromo-1-(4-chlorophenyl) ethanone in the presence of sodium ethoxide gave the corresponding product
yielded the corresponding 2-substituted-1,2,4-triazole-3-one, 16, which was reduced to 1,2,4-triazoles (17). Synthesis of
compounds 18, 19, and 20 were carried out starting from compounds 17 with 4-chlorobenzyl chloride (for 18), 2,4-
dichlorobenzyl chloride (for 19), and 2,6-dichlorobenzyl chloride (for 20).
Method:
The conventional technique was utilized for the synthesis of compounds, 3-7, and microwave-assisted technique
for the compounds, 8-20. That is, green chemistry techniques were applied during these reactions. The structures molecules
were elucidated on the foundation of 1H NMR, 13C NMR, FT-IR, EI-MS methods, and elemental analysis. Novel
synthesized molecules were investigated for their antimicrobial activity using MIC (minimum inhibitory concentration)
method.
Results and Discussion:
Aminoalkylation of triazole derivatives 3 and 7a–c with fluoroquinolones such as ciprofloxacin
and norfloxacin provided an enhancement to the bioactivity of Mannich bases 8-11 against the tested microorganisms. The
MIC values ranged between <0.24 and 3.9 μg/mL”. Moreover, molecules 10 and 11 have more effective on M. smegmatis
than the other compounds by the MIC values of <1 μg/mL. They have shown very good antituberculosis activity.
Conclusion:
Most of the synthesized structures were observed to have excellent antimicrobial activity against most microorganisms taken into account. These molecules have activity better than the standard drug ampicillin and streptomycin.
Microwave Assisted Synthesis of Some Biologically Active Benzothiazolotriazine Derivatives