Synthesis, Antimicrobial Studies, and Docking Simulations of New Bis(4,5‐dihydropyrazole) Derivatives

Abstract

A novel series of bis(3-thienyl-4,5-dihydropyrazoles) has been synthesized by the cyclization reactions of bischalcones with phenyl hydrazine in basic medium. The O-alkylation reactions of chalcones with suitable 1,ω-dibromoalkanes in the presence of anhydrous K 2 CO 3 , dry acetone, and Bu 4 N + I À as PTC lead to the formation of bischalcones in good yields. The chalcone required was obtained from the Claisen-Schmidt condensation reaction of 2-acetylthiophene with 3-hydroxybenzaldehyde. Structures of prepared compounds were elucidated from their IR, 1 H-NMR, 13 C-NMR, and ESI-MS spectral data. Newly synthesized compounds were screened for their antimicrobial potencies against Gram-positive, Gram-negative bacterial strains, and fungal strains using serial tube dilution method. Docking simulations have also been carried out to visualize the possible interaction of synthesized scaffold 2(a-g) and 3(a-g) at the active sites of Escherichia coli. 1 H-NMR (400 MHz) spectra of 2(a-g), two broad doublets centered at δ 7.83-7.43 and 7.68-7.63 were easily assigned to H-3 and H-2. The coupling value of J 2,3 = 15.6 Hz describes the trans geometry around the C-2 and C-3 double bond. The thiophen ring protons H-3 0 , H-5 0 , and H-4 0 were found to be resonating in the aromatic region at δ 8.22-7.84 (dd, J 3 0 5 0 =1.1-0.8 Hz, J 3 0 ,4 0 =3.8-3.9 Hz), 7.90-7.63 (dd, J 5 0 ,3 0 = 0.6-1.0 Hz, J 5 0 ,4 0 = 4.8-5.0 Hz), and 7.24-7.18 (dd, J 4 0 ,3 0 = 3.8-3.9 Hz, J 4 0 ,5 0 =4.8-5.0 Hz), respectively. The OCH 2 group protons belonging to aliphatic linkers were placed at δ 4.27-4.03 (J vic = 6.7 Hz) as four protons triplets.

Synthesis, characterization & in vitro antimicrobial‐antioxidant studies of novel N,1‐diphenyl‐4,5‐dihydro‐1H‐1,2,4‐triazol‐3‐amine derivatives

“…The reaction mixture was cooled and provided an off white solid, which was filtered and dried. To obtain pure product, the resulting solid was crystallized using methanol as solvent 4a …”

“…To obtain pure product, the resulting solid was crystallized using methanol as solvent 4a. [36] 4a: off white solid; yield: 84%; m.p. : 112°C to 114°C; IR (KBr) υ max (cm…”

Multicomponent synthesis of new bis(pyranpyrazole) and their antimicrobial-antioxidant evaluations

“…With the best of our efforts, only three papers incorporating the study of bispyranopyrazoles could be found. [36][37][38] In continuation of an ongoing study on bisheterocycles, [39][40][41][42][43][44] the present research work was focused on the synthesis of new rigid chain linked bis(pyranopyrazoles) 3a-f using three component condensation reactions of malononitrile, pyrazolone and dibenzaldehydes. The major impetus behind these investigations was to study the antimicrobial and antioxidant properties of the newly prepared symmetrical bisheterocycles.…”

New Biphenyl‐Based Bispyrazolines: Synthesis, Antimicrobial, and Docking Studies

“…The developments of the new proficient antibacterial therapies are the significant alternatives treatments for the conventional drug resistance bacteria and fungi . So to control the various infectious diseases and increasing microbial resistance, synthetic chemists have been organizing their researches upon the designing and preparations of the broad spectrum antimicrobial .…”