Design, synthesis and biological activities of some 7-aminocephalosporanic acid derivatives

Chemoselective Reactions of Functionalized Sulfonyl Halides

Chemoselective transformations of functionalized sulfonyl fluorides and chlorides are surveyed comprehensively. It is shown that sulfonyl fluorides provide an excellent selectivity control in their reactions. Thus, numerous conditions are tolerated by the SO2 F group - from amide and ester formation to directed ortho-lithiation and transition-metal-catalyzed cross-couplings. Meanwhile, sulfur (VI) fluoride exchange (SuFEx) is also compatible with numerous functional groups, thus confirming its title of "another click reaction". On the contrary, with a few exceptions, most transformations of functionalized sulfonyl chlorides typically occur at the SO2 Cl moiety.

Microwave-assisted Synthesis of Novel Mannich Base and Conazole Derivatives Containing Biologically Active Pharmacological Groups

Background:

The aim of this study was 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 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 was 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).

Methods:

he 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 of 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:

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 exhibited more effects 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 better activity than the standard drug ampicillin and streptomycin.

Piperazine-azole-fluoroquinolone hybrids: Conventional and microwave irradiated synthesis, biological activity screening and molecular docking studies

A series of new 1,2,4-triazole and 1,3,4-oxadiazole derivatives was obtained via several steps sequential reactions of phenyl piperazine. Then, these compounds were converted to the corresponding fluoroquinolone hybrids via one pot three component Mannich reaction. All the reactions were examined under conventional and microwave mediated conditions, and optimum conditions were determined. The effect of different solvents and microwave power on microwave prompted reactions was investigated as well. All the newly synthesized compounds were characterized by FTIR, ¹H NMR, ¹³C NMR and EI MS spectral techniques. The antimicrobial activity, DNA gyrase and Topoisomerase IV inhibition potentials were performed. The results obtained showed that fluoroquinolone hybrids possess good antimicrobial activity. Moreover, Fluoroquinolone-azole-piperazine hybrids synthesized in the present study displayed excellent DNA gyrase inhibition. To unveil the interaction mode of compounds to receptor, a molecular docking study was performed. With an average least binding energy of -9.5 kcal/mol, all compounds were found to have remarkable inhibitory potentials against DNA gyrase (E. coli).

Synthesis and antimicrobial activity evaluation of new norfloxacine-azole hybrids

Norfloxacin-azole hybrids 3 and 6a,b were synthesized starting from norfloxacin. The treatment of these compounds with amines as a one-pot three-component reaction produced the corresponding amino derivatives 4a,b, 7a–g and 8a,b in good yields. The conventional and microwave-assisted methods were used with the latter method being more efficient. The structures of the synthesized compounds were characterized by elemental analysis, IR, 1H NMR, 13C NMR and MS. All compounds were screened for their antimicrobial activities. Most of them exhibit excellent antibacterial activity but are not active against selected fungi.

Microwave-assisted and conventional synthesis of novel antimicrobial 1,2,4-triazole derivatives containing nalidixic acid skeleton

Carbothioamides