Showing papers on "Hydrazone published in 2019"

Synthesis and Anticancer Activity of New ((Furan-2-yl)-1,3,4-thiadiazolyl)-1,3,4-oxadiazole Acyclic Sugar Derivatives.

Abstract: New sugar hydrazones incorporating furan and/or 1,3,4-thiadiazole ring systems were synthesized by reaction of the corresponding hydrazide with different aldose sugars. Heterocyclization of the formed hydrazones afforded the derived acyclic nucleoside analogues possessing the 1,3,4-oxadiazoline as modified nucleobase via acetylation followed by the heterocyclization process. The anticancer activity of the synthesized compounds was studied against human liver carcinoma cell (HepG-2) and at human normal retina pigmented epithelium cells (RPE-1). High activities were revealed by compounds 3, 12 and 14 with IC50 values near to that of the reference drug doxorubicin.

Design, synthesis, in silico docking studies and biological evaluation of novel quinoxaline-hydrazide hydrazone-1,2,3-triazole hybrids as α-glucosidase inhibitors and antioxidants

Abstract: A new series of quinoxaline-hydrazidehydrazone-1,2,3-triazole hybrids, 14a–j, 15a–j and 16a–e, was designed, synthesized and screened for in vitro α-glucosidase and antioxidant activities. For the synthesis of the target compounds, quinoxaline hydrazides were condensed with benzaldehyde triazoles in the presence of AcOH (cat) in ethanol. The key step in the preparation of compounds 8a–j was the Cu(I)-catalyzed [3+2] cycloaddition reaction (CuAAC) with appropriate alkynes (6, 7) and azides, and 13a–j were prepared from simple aldehydes utilizing the same click reaction as the final step. Quinoxaline hydrazides (3, 3a) were synthesized from o-phenylenediamine and pyruvic acid via three-step reactions comprising cyclization, alkylation and hydrazidation. Among these hybrids, 14a (IC50 = 21.92 μg mL−1), 14b (IC50 = 22.32 μg mL−1), 14c (IC50 = 23.58 μg mL−1) and 15a (IC50 = 24.50 μg mL−1) showed good α-glucosidase inhibition compared with the standard acarbose (IC50 = 22.32 μg mL−1). Further, the scavenging abilities of the synthesized compounds as antioxidants were studied using the DPPH, H2O2, and NO methods; as per the obtained results, compounds 14a, 14b, 14c and 15a displayed good antioxidant activity. Docking studies of the active compounds and acarbose as a standard with α-glucosidase (PDB ID: 2ZEO) were performed to determine the molecular interactions between the inhibitors and the active site of the enzyme. Better binding energies of the active compounds than of the standard acarbose were observed. Therefore, our new hybrid molecules may be useful for further optimization in developing new lead molecules with both α-glucosidase inhibition and antioxidant activities.

An Old Dog with New Tricks: Enjoin Wolff–Kishner Reduction for Alcohol Deoxygenation and C–C Bond Formations

Abstract: The Wolff–Kishner reduction, discovered in the early 1910s, is a fundamental and effective tool to convert carbonyls into methylenes via deoxygenation under strongly basic conditions. For over a century, numerous valuable chemical products have been synthesized by this classical method. The reaction proceeds via the reversible formation of hydrazone followed by deprotonation with the strong base to give an N-anionic intermediate, which affords the deoxygenation product upon denitrogenation and protonation. By examining the mechanistic pathway of this century old classical carbonyl deoxygenation, we envisioned and subsequently developed two unprecedented new types of chemical transformations: a) alcohol deoxygenation and b) C–C bond formations with various electrophiles including Grignard-type reaction, conjugate addition, olefination, and diverse cross-coupling reactions. 1 Introduction 2 Background 3 Alcohol Deoxygenation 3.1 Ir-Catalyzed Alcohol Deoxygenation 3.2 Ru-Catalyzed Alcohol Deoxygenation 3.3 Mn-Catalyzed Alcohol Deoxygenation 4 Grignard-Type Reactions 4.1 Ru-Catalyzed Addition of Hydrazones with Aldehydes and Ketones 4.2 Ru-Catalyzed Addition of Hydrazone with Imines 4.3 Ru-Catalyzed Addition of Hydrazone with CO2 4.4 Fe-Catalyzed Addition of Hydrazones 5 Conjugate Addition Reactions 5.1 Ru-Catalyzed Conjugate Addition Reactions 5.2 Fe-Catalyzed Conjugate Addition Reactions 6 Cross-Coupling Reactions 6.1 Ni-Catalyzed Negishi-type Coupling 6.2 Pd-Catalyzed Tsuji–Trost Alkylation Reaction 7 Other Reactions 7.1 Olefination 7.2 Heck-Type Reaction 7.3 Ullmann-Type Reaction 8 Conclusion and Outlook

Synthesis of Anthranilic Diamide Derivatives Containing Moieties of Trifluoromethylpyridine and Hydrazone as Potential Anti-Viral Agents for Plants.

Abstract: A series of novel anthranilic diamide derivatives (5a–5ab) containing moieties of trifluoromethylpyridine and hydrazone was designed and synthesized. The synthesized compounds were evaluated in viv...

Fabrication of a Hydrazone-Based Al(III)-Selective "Turn-On" Fluorescent Chemosensor and Ensuing Potential Recognition of Picric Acid.

Abstract: A hydrazone-based N′1,N′3-bis((E)-4-(diethylamino)-2–hydroxybenzylidene)isophthalohydrazide (NDHIPH), has been synthesized, characterized, and assessed for its highly selective and sensitive (limit...

Expedient synthesis of E-hydrazone esters and 1H-indazole scaffolds through heterogeneous single-atom platinum catalysis

Abstract: Unprotected E-hydrazone esters are prized building blocks for the preparation of 1H-indazoles and countless other N-containing biologically active molecules. Despite previous advances, efficient and stereoselective synthesis of these compounds remains nontrivial. Here, we show that Pt single atoms anchored on defect-rich CeO2 nanorods (Pt1/CeO2), in conjunction with the alcoholysis of ammonia borane, promotes exceptionally E-selective hydrogenation of α-diazoesters to afford a wide assortment of N-H hydrazone esters with an overall turnover frequency of up to 566 hours-1 upon reaction completion. The α-diazoester substrates could be generated in situ from readily available carboxylic esters in one-pot hydrogenation reaction. Utility is demonstrated through concise, scalable synthesis of 1H-indazole-derived pharmaceuticals and their 15N-labeled analogs. The present protocol highlights a key mechanistic nuance wherein simultaneous coordination of a Pt site with the diazo N═N and ester carbonyl motifs plays a central role in controlling stereoselectivity, which is supported by density functional theory calculations.

Synthesis, Solvatochromic Performance, pH Sensing, Dyeing Ability, and Antimicrobial Activity of Novel Hydrazone Dyestuffs

Abstract: New tricyanofuran intramolecular charge transfer dyes comprising the hydrazone group were prepared and fully characterized in order to study their possible solvatochromism, dyeing ability, and antimicrobial activity. The preparation of the hydrazone dyes was achieved in relatively good yields starting from different aromatic amines. The hydrazone functional group was presented via the azo-coupling reaction of the tricyanofuran compound by the properly substituted diazonium chloride. Chemical structures of the prepared hydrazones were confirmed via nuclear magnetic resonance spectroscopy (1H- and 13C-NMR), Fourier-transform infrared spectroscopy (FT-IR), and elemental analysis (C, H, and N). The UV-visible absorption spectra of the produced sensor colorants displayed interesting solvatochromism in solvents with a different polarity, which was found to be affected by the substituents bonded to the aromatic hydrazone moiety. The pH molecular switching was investigated through tuning the intramolecular charge transfer stimulated by the reversible deprotonation/protonation process in acetonitrile solution showing color change from yellow to purple. The produced disperse dyestuffs were employed for dyeing polyester fibers to introduce acceptable color strength and colorfastness properties. Moreover, the dyes verified a weak to moderate antimicrobial activity against some selected pathogens, including S. aureus, E. coli, and Candida albicans.

Synthesis, Characterization, Free-radical Scavenging Capacity and Antioxidant Activity of Novel Series of Hydrazone, 1,3,4-oxadiazole and 1,2,4- triazole Derived from 3,5-dimethyl-1H-pyrazole

Abstract: Pyrazole is an important class of heterocyclic compound, has been shown to exhibit diverse biological and pharmacological activities such as anti-inflammatory, anti-cancer, antioxidant, etc. In this study, a series of novel 3,5-dimethyl-1H-pyrazole derivatives containing hydrazine 4a-l have been synthesized via the reaction of the 2-(3,5-dimethyl-1H-pyrazol-1-yl)acetohydrazide. All synthesized compounds have been tested for their in vitro antioxidant activities via utilization of 1,1-biphenyl-2-picrylhydrazyl (DPPH) as a free radical scavenging reagent. The data reported herein indicates that compound 4k showed potential radical scavenging capacity and compounds 4f and 4g exhibited best activity for the iron binding while comparing with positive controls. Good activity was noted for some compounds. In particular, compound 4k showed the highest antioxidant activity with IC50 values of 22.79 ± 3.64 and 1.35 ± 0.66 μg/mL in the DPPH and ABTS tests, respectively.

Design, Synthesis and Anti-tuberculosis Activity of Hydrazones and N-acylhydrazones Containing Vitamin B6 and Different Heteroaromatic Nucleus

Abstract: Background: The term vitamin B6 refers to a set of six compounds, pyridoxine, pyridoxal ,and pyridoxamine and their phosphorylated forms, among which pyridoxal 5´-phosphate (PLP) is the most important and active form acting as a critical cofactor. These compounds are very useful in medicinal chemistry because of their structure and functionalities and are also used in bioinorganic chemistry as ligands for complexation with metals. Methods: In this study, a series of hydrazones 1a-g and N-acylhydrazones 2a-f containing vitamin B6 have been synthesized from commercial pyridoxal hydrochloride and the appropriate aromatic or heteroaromatic hydrazine or N-acylhydrazine. All synthesized compounds have been fully characterized and tested against Mycobacterium tuberculosis. Results: Among the N-acylhydrazones derivatives 2a-f, 2d (para- pyridine substituted Nacylhydrazone; MIC = 10.90 μM) exhibited the best activity. The ortho-pyridine derivative 2b exhibited intermediate activity (MIC = 87.32 μM), and the meta-pyridine derivative 2c was inactive. In case of the hydrazone series 1a-g, 7-chloroquinoxaline derivative 1f (MIC = 72.72 μM) showed the best result, indicating that the number of nitrogen and chlorine atoms in the radical moiety play an important role in the anti-tuberculosis activity of the quinoxaline derivatives (1f and 1g). Conclusion: The data reported herein indicates that the isoniazid derivative 2d (MIC = 10.90 μM) exhibited the best activity in the N-acylhydrazone series and; the quinoxaline nucleus derivative 1f (MIC = 72.72 μM) was the most active compound in the hydrazone series.

Synthesis and Spectral Characterization of Asymmetric Azines Containing a Coumarin Moiety: The Discovery of New Antimicrobial and Antioxidant Agents.

Abstract: Nine unsymmetrical azines containing a coumarin moiety were prepared by the reaction of the hydrazone of 4-hydroxy-3-acetylcoumarin with differently substituted aromatic aldehydes. The azines were fully spectrally characterized, including a complete assignment of 1 H- and 13 C-NMR resonances, and were assessed for their acute toxicities in the Artemia salina model. Their free radical scavenging activities were tested in the DPPH assay, and in vitro antimicrobial activities were determined against seven bacterial and two fungal strains. The azines containing a p-hydroxyphenyl group were shown to be the most effective antimicrobial agents, and in the case of resistant strains of Staphylococcus aureus and Acinetobacter baumannii, the activity was comparable to that of chloramphenicol. The derivative having a 3,5-dimethoxy-4-hydroxyphenyl group exhibited pronounced antioxidant power reacting rapidly and in 1 : 1 mol ratio with the DPPH radical.