Synthesis of novel Schiff bases using 2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile and 1,3-Disubstituted pyrazole-4-carboxaldehydes derivatives and their antimicrobial activity

Abstract

2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile have been synthesized from 1-(3-fluoro-4-methoxyphenyl)ethanone, malononitrile, a mild base and sulfur powder using Gewald synthesis technique and the intermediate was treated with 1,3-disubstituted pyrazole-4-carboxaldehyde to obtain the novel Schiff bases. 1,3-disubstituted pyrazole-4-carboxaldehyde derivatives have been synthesized by Vilsmeier-Haack reaction in the course of a multi-step reaction. The structure of novel compounds were established on the basis of their elemental analyses IR, 1 H NMR, 13 C NMR, and mass spectral data and then screened for their in vitro antimicrobial activity. Among them 5a, 5c, 5f and 5h showed excellent activity when compared to other derivatives. Remaining derivatives showed moderate activity.

Novel pyrazole‐clubbed thiophene derivatives via Gewald synthesis as antibacterial and anti‐inflammatory agents

“…The crude product was recrystallized from ethyl acetate and toluene mixture to afford the title compound in a 75% yield. 4.1.5 | General procedure for the synthesis of 1,3-diaryl-1H-pyrazole-4-carbaldehydes 7a-p [30] Phosphorus oxychloride (6.…”

“…General synthetic procedure for 2-amino-5-(2,4-dichlorophenyl)thiophene-3-carbonitrile (3)[30] A mixture of 2-[1-(2,4-dichlorophenyl)ethylidene]malononitrile (2; 1 mmol) and sulfur powder (1.3 mmol) was suspended in THF(25 ml) and warmed to an internal temperature of 35°C. A solution of sodium bicarbonate (1.4 mmol) in 5 ml of water was added over a period of 1 hr.…”

“…The crude product was recrystallized from toluene and ethyl acetate mixture to afford compound 3 in a 75% yield. General procedure for synthesis of 1-(aryl)-2-[1-(aryl)ethylidene]hydrazines 6a-p[30] To a solution of substituted acetophenones 4a-h (5 g, 19 mmol) in methanol (40 ml), substituted phenyl hydrazine 5a, 5b (2.1 g, 19 mmol) was added, followed by glacial acetic acid(15 ml), at room temperature. The resulting reaction mixture was heated to reflux for 4 hr.…”

Discovery of New Schiff Bases Tethered Pyrazole Moiety: Design, Synthesis, Biological Evaluation, and Molecular Docking Study as Dual Targeting DHFR/DNA Gyrase Inhibitors with Immunomodulatory Activity

“…On the other hand, pyrazole moiety containing both N-(4-chlorophenyl) and (2-fluorophenyl)acrylamide derivative (VI) produced potent antifungal activity [19]. Recently, there is a growing interest in the synthesis of Schiff bases tethered pyrazole ring because of their importance in biological activities [20][21][22]. For example, Schiff base (VII), bearing imidazole and pyrazole nucleus, showed potency against E. coli [23].…”

Novel piperazine–chalcone hybrids and related pyrazoline analogues targeting VEGFR-2 kinase; design, synthesis, molecular docking studies, and anticancer evaluation

“…N-aryl piperazine derivatives are important organic compounds that have recently attracted considerable interest for their anticancer activity [20][21][22][23] . On the other hand, pyrazole a simple aromatic five-membered ring contains two adjacent nitrogen atoms is included in many derivatives that display a variety of pharmacological activities such as anti-Alzheimer disease 24 , anticonvulsant 25,26 , anti-tubercular 27,28 , anti-microbial 29,30 , anti-inflammatory, and analgesic 31,32 . Numerous pyrazole derivatives have proved their anti-cancer efficacy against different types of cancer [33][34][35][36][37][38] .…”