Showing papers on "Hydrazone published in 2021"

Carbonyl umpolung as an organometallic reagent surrogate.

Abstract: Construction of new carbon–carbon bonds is the cornerstone of organic chemistry. Organometallic reagents are amongst the most robust and versatile nucleophiles for this purpose. Polarization of the metal–carbon bonds in these reagents facilitates their reactions with a vast array of electrophiles to achieve chemical diversification. The dependence on stoichiometric quantities of metals and often organic halides as feedstock precursors, which in turn produces copious amounts of metal halide waste, is the key limitation of the classical organometallic reactions. Inspired by the classical Wolff–Kishner reduction converting carbonyl groups in aldehydes or ketones into methylene derivatives, our group has recently developed strategies to couple various alcohols, aldehydes, and ketones with a broad range of both hard and soft carbon electrophiles in the presence of catalytic amounts of transition metals, via the hydrazone derivatives: i.e., as organometallic reagent surrogates. This Tutorial Review describes the chronological development of this concept in our research group, detailing its creation in the context of a deoxygenation reaction and evolution to a more general carbon–carbon bond-forming strategy. The latter is demonstrated by the employment of carbonyl-derived alkyl carbanions in various transition-metal catalyzed chemical transformations, including 1,2-carbonyl/imine addition, conjugate addition, carboxylation, olefination, cross-coupling, allylation, alkylation and hydroalkylation.

Synthesis, spectral, magnetic, DFT calculations, antimicrobial studies and phenoxazinone synthase biomimetic catalytic activity of new binary and ternary Cu(II), Ni(II) and Co(II) complexes of a tridentate ONO hydrazone ligand

Abstract: New mononuclear copper(II), nickel(II) and cobalt(II) hydrazone complexes of 2-cyano-N′-((4-oxo-4H-chromen-3-yl)methylene)acetohydrazide have been synthesized. Structure identification of the prepa...

Synthesis, admetSAR Predictions, DPPH Radical Scavenging Activity, and Potent Anti-mycobacterial Studies of Hydrazones of Substituted 4-(anilino methyl) benzohydrazides (Part 2).

Abstract: Background For the past several decades, we are remarking presence of the tuberculosis (TB) as the most common infectious disease leading mortality. Objective Hydrazone containing azometine group (-NHN=CH-) compounds has been reported for broad range of bioactivities such as antiplatelet, analgesic, antiinflammatory, anticonvulsant, antidepressant, antimalarial, vasodilator , antiviral and antimicrobial, etc. Method: For synthesis of our compounds (4a-4d) and (6a-6e), we have treated aromatic amines with methyl terephthalaldehydate in methanol giving us Schiff's bases followed by reductive amination and further treatment with hydrazine hydrate to give acid hydrazides (4a-4d). These acid hydrazides were then treated with different aromatic aldehydes to yield hydrazones (6a-6d). All our synthesized compounds were subjected to FT-IR, NMR, and UV spectroscopic characterization. Results Compounds (4a-4d) and (6a-6e) were found to have highly potent activity against Mycobacteria tuberculosis (Vaccine strain, H37 RV strains): ATCC No- 27294 (MIC:1.6-6.25 μg/mL) than standard anti-TB drugs. Our compounds exhibited good radical scavenging potentials(0-69.2%) as checked from DPPH protocol. All compounds also demonstrated good in-silico ADMET results. Conclusion Our current study revealed promising in-vitro antituberculosis and antioxidant profiles of hydrazidehydrazone analogues.

Development of a novel colorimetric thermometer based on poly(N-vinylcaprolactam) with push–π–pull tricyanofuran hydrazone anion dye

Abstract: Thermochromic poly(N-vinylcaprolactam-co-tricyanofuran hydrazone) [poly(VC-co-TCFH)] gel labeled with a halochromic chromophore was developed using traditional free radical polymerization. A novel vinyl-containing tricyanofuran hydrazone (TCFH) halochromic chromophore bearing a hydrazone sensor group was generated via an azo-coupling procedure of a tricyanofyran (TCF) heterocycle with the diazonium chloride salt of 2-hydroxy-4-nitroaniline comprising an allyl group. The molecular structures of the TCFH chromophore and related intermediates were proved by different techniques, including FT-IR, mass spectroscopy (MS), 1H/13C NMR and elemental analyses (C, H, N). This chromophore showed a pronounced solvatochromic activity in various organic solvents of different polarities. pH sensing activity was also monitored at different pH values. Both solvatochromism and pH-responsiveness can be ascribed to the delocalization of charge on TCFH. Poly(VC-co-TCFH) acted as a thermochromic sensor device generating immediate colorimetric changes from yellow to orange, red, wine, violet, and purple with increasing temperature of aqueous poly(VC-co-TCFH) solution. Such colorimetric changes are proportionally interrelated with the temperature increase from 33 to 47 °C due to a phase change in an aqueous solution of poly(VC-co-TCFH) copolymer. The poly(VC-co-TCFH) copolymer composed of N-vinylcaprolactam (VC) and push–π–pull hydrazone type tricyanofuran chromophore monomers functions as a temperature-driven chromogenic thermometer. The morphology of the gel nanostructure was monitored by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Mechanistic studies accounting for solvatochromism and halochromism of TCFH as well as thermochromism of poly(VC-co-TCFH) are proposed.

Synthesis, In silico and In vitro Analysis of Hydrazones as Potential Antituberculosis Agents.

Abstract: Tuberculosis (TB) is a major cause of mortality and illness as reported by the W.H.O in 2019. The WHO report also mentioned the fact that about 10.0 million people fell ill with tuberculosis in the year 2018. Hydrazide-hydrazones having azomethine group (-NH-N=CH-) connected with carbonyl group is reported for the number of bioactivities like anti-inflammatory, anticonvulsant, anticancer, antiviral and antiprotozoal. OBJECTIVE The objective of our current study is to design and synthesise more potent hydrazide- hydrazones, containing anti-tubercular agents. METHODS In the current study, we synthesized 10 hydrazones (3a-3j) by stirring corresponding benzohydrazides (2) with substituted aldehydes (1a-j) in ethanol as a solvent and acetic acid as a catalyst at room temperature. All synthesized compounds were characterized by various spectroscopic techniques including elemental analysis, ultraviolet-visible spectroscopy, fluorescence, fourier- transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Compounds (3a-3j) were tested for in vitro anti-TB activity using Microplate Alamar Blue Assay (MABA). RESULTS All our synthesized compounds (3a-3j) were found to be potent against Mycobacteria tuberculosis (H37RV strain) with MIC (minimum inhibitory concentrations) values of 3.125-50 μg/mL. The hydrazide CO-NH protons in (3a-j) compounds are highly deshielded and showed broad singlet at 9.520-9.168 ppm. All the compounds were found to have more intense emission in the 416 - 429 nm regions and strong absorption in the regions of 316 - 327 nm. Synthesized compounds were also tested for in silico analysis using different software for their Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) analysis. All the compounds were found to be in silico non-carcinogenic. CONCLUSION It will be worth saying that our in silico and in vitro approaches used in the current study will become a guide for medicinal chemists to make structural modifications and synthesize more effective and potent hydrazone containing anti-tubercular agents.

N,N-Dialkylhydrazones as Versatile Umpolung Reagents in Enantioselective Anion-Binding Catalysis.

Abstract: An enantioselective anion-binding organocatalytic approach with versatile N,N-dialkylhydrazones (DAHs) as polarity-reversed (umpolung) nucleophiles is presented. For the application of this concept, a highly ordered hydrogen-bond (HB) network between a carefully selected CF3 -substituted triazole-based multidentate HB-donor catalyst, the ionic substrate and the hydrazone in a supramolecular chiral ion-pair complex was envisioned. The formation of such a network was further supported by both experimental and computational studies, which showed the crucial role of the anion as a template unit. The asymmetric Reissert-type reaction of quinolines as a model test reaction chemoselectively delivered highly enantiomerically enriched hydrazones (up 95:5 e.r.) that could be further derivatized to value-added compounds with up to three stereocenters.

Interaction of pyridoxal-derived hydrazones with anions and Co2+, Co3+, Ni2+, Zn2+ cations

Abstract: Present paper reports on the interactions between four hydrazones derived from pyridoxal and hydrazides of 2-furoic, thiophene-2-carboxylic, pyrazinoic and pyridine-3-carboxylic acids and 10 differ...

Synthesis and anticancer properties of novel hydrazone derivatives incorporating pyridine and isatin moieties

Abstract: Nine novel hydrazone derivatives (4a-i) incorporating pyridine and isatin moieties were synthesized through one-pot, four-component heterocyclic condensation reactions. The structures of all new compounds (2a-e, 3a, 3c-e, and 4a-e) were identified by 1 H nuclear magnetic resonance (NMR), 13 C NMR, and Fourier-transform infrared spectroscopic techniques and elemental analysis. Cell viability assays for the tested hydrazone derivatives were performed and the log IC50 values of the compounds were calculated after a 24-h treatment. All hydrazide derivatives tested showed a promising antitumor activity against A-2780 cells as compared with the standard drug docetaxel with a log IC50 value of 0.2200 μM (p < .05). Seven of the examined compounds (4b-e, 4g-i) showed high cytotoxic activity against A-2780 cells as compared with the standard drug docetaxel. Whereas the log IC50 of docetaxel was 0.2200 μM for A-2780 cells at 24 h, the IC50 values of these compounds were -0.4987, -0.4044, -0.8138, -0.3868, -0.6954, -0.4751, and 0.1809 μM, respectively. Three of the compounds, 4b, 4d, and 4i, showed high cytotoxic activity against MCF-7 cells as compared with docetaxel (p < .05). Whereas the log IC50 of docetaxel was 0.2400 μM for MCF-7 cells at 24 h, the log IC50 values of compounds 4b, 4d, and 4i were -0.1293, -0.1700, and 0.2459 μM, respectively.

Synthesis of spiro(indoline-2,3′-hydropyridazine) via an “on-water” [4 + 2] annulation reaction

Abstract: An on-water [4 + 2] annulation reaction between the 2-methyl-3H-indolium salt and α-bromo N-acyl hydrazone has been developed. The environmentally friendly strategy provides the first facile access to spiro(indoline-2,3′-hydropyridazine) scaffolds. Compared with the reaction in organic solvents, the use of water as the sole solvent remarkably improves the reaction efficiency as well as chemoselectivity. This green protocol features high yield, broad substrate scope, and mild reaction conditions.

A Visual and Ratiometric Chemosensor Using Thiophene Functionalized Hydrazone for the Selective Sensing of Pb2+ and F− Ions

Abstract: Herein, a simple, efficient ratiometric chemosensor was reported for the selective sensing of Pb2+ and F− ions using thiophene functionalized hydrazone as a chemical probe. Hydrazone moiety was developed by utilizing thiophene/naphthalene as a platform for the particular recognition of cation and anion. The structures of the precursor (Z)-(1-(5-bromothiophen-2-yl)ethylidene)hydrazine (ABTH) and the final probe 1-((Z)-(((Z)-1-(5-bromothiophen-2-yl)ethylidene)hydrazono)methyl)naphthalen-2-ol (NAPABTH) were confirmed by 1H, 13C-NMR and LC-MS spectroscopic methods. The interaction of NAPABTH with Pb2+ and F− ions was visually observed by the formation of pink and dark yellow solutions, respectively. The detection limits were found to be very low for Pb2+ as 1.06 ppm and for F− ions as 3.72 nM. This visual detection of Pb2+/F− ions with satisfactory outcomes obtained from UV-Vis titrations. The sensing mechanistic pathways and stoichiometric ratios were obtained from DFT and Job’s plot, respectively. The observed results are highly promising as highly selective chemosensor with lower detection limits for Pb2+ and F− ions. This strategy could exhibit tremendous applications for the selective sensing of heavy metal cations with rapid sensitivity for the design of new devices.