Showing papers on "Hydrazone published in 2016"
TL;DR: An unprecedented visible-light-induced direct C-H bond difluoroalkylation of aldehyde-derived hydrazones was developed, which represents a new way to synthesize substituted hydrazone synthesis rather than classical amine synthesis.
Abstract: An unprecedented visible-light-induced direct C−H bond difluoroalkylation of aldehyde-derived hydrazones was developed. This reaction represents a new way to synthesize substituted hydrazones. The salient features of this reaction include difluorinated hydrazone synthesis rather than classical amine synthesis, extremely mild reaction conditions, high efficiency, wide substrate scope, ease in further transformations of the products, and one-pot syntheses. Mechanistic analyses and theoretical calculations indicate that this reaction is enabled by a novel aminyl radical/polar crossover mechanism, with the aminyl radical being oxidized into the corresponding aminyl cation through a single electron transfer (SET) process.
164 citations
TL;DR: An efficient palladium-catalyzed asymmetric synthesis of axially chiral vinyl arenes from aryl bromides and hydrazones is reported.
Abstract: An efficient palladium-catalyzed asymmetric synthesis of axially chiral vinyl arenes from aryl bromides and hydrazones is reported. The products were easily oxidized to axially chiral biaryl compounds, and the phosphine oxides were readily reduced to phosphine ligands.
138 citations
TL;DR: An experimental investigation on the effects of hydrazine treatment on graphene oxide via a reaction-model approach using small conjugated aromatic compounds containing various oxygen functional groups to mimic the structure of graphene oxide.
105 citations
TL;DR: A new hydrazone-based exo-directing group (DG) strategy developed for the functionalization of unactivated primary β C-H bonds of aliphatic amines and can be readily removed, and a one-pot C-H acetoxylation/DG removal protocol was also discovered.
Abstract: Described is a new hydrazone-based exo-directing group (DG) strategy developed for the functionalization of unactivated primary β C−H bonds of aliphatic amines. Conveniently synthesized from protected primary amines, the hydrazone DGs are shown to site-selectively promote the β-acetoxylation and tosyloxylation via five-membered exo-palladacycles. Amines with a wide scope of skeletons and functional groups are tolerated. Moreover, the hydrazone DG can be readily removed, and a one-pot C−H acetoxylation/DG removal protocol was also discovered.
73 citations
TL;DR: A TBAI-catalyzed reaction between N-tosyl hydrazone and sulfur was developed, leading to 1,2,3-thiadiazoles in moderate to good yields, which serves as an improvement for the Hurd-Mori reaction.
Abstract: A TBAI-catalyzed reaction between N-tosyl hydrazone and sulfur was developed, leading to 1,2,3-thiadiazoles in moderate to good yields. It represents a facile and practical procedure to access thiadiazole under metal-free conditions. This procedure serves as an improvement for the Hurd–Mori reaction.
65 citations
TL;DR: A palladium-catalyzed C(sp(2))-H difluoromethylation of aldehyde-derived hydrazones using bromodifluolorometHylated compounds to afford the corresponding functionalized diffluorometrichylketonehydrazones has been established and it is proposed that a radical/SET mechanism proceeding via a dif fluoroalkyl radical may be involved in the catalytic cycle.
Abstract: A palladium-catalyzed C(sp2)−H difluoromethylation of aldehyde-derived hydrazones using bromodifluoromethylated compounds to afford the corresponding functionalized difluoromethylketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a difluoroalkyl radical may be involved in the catalytic cycle. Applications of the methodology to the synthesis of α,α-difluoro-β-ketoesters and α,α-difluoroketones (RCOCF2H) have been illustrated.
59 citations
TL;DR: In this paper, five new mono- or di-organotin(IV) complexes, Me2SnL (1), Ph2NLLL (2), n-Bu2NCL(H2O)L·CH3CH2OH (5), were synthesized and characterized by elemental analysis and spectroscopic techniques (IR and 1H, 13C, 119Sn NMR).
Abstract: Five new mono- or di-organotin(IV) complexes, Me2SnL (1), Ph2SnL (2), n-Bu2SnL (3), n-Oct2SnL (4) and n-BuSnCl(H2O)L·CH3CH2OH (5), where H2L is 2-hydroxy-N′-[(2-hydroxy-3-methoxyphenyl)methylidene]-benzohydrazone, were synthesized and characterized by elemental analysis and spectroscopic techniques (IR and 1H, 13C, 119Sn NMR). The crystal structures of all compounds were established by X-ray diffraction, showing the hydrazone Schiff base ligand bound to the tin atom as ONO tridentate chelate. In vitro cytotoxicity determination reveals that all compounds exhibit good activity toward three cisplatin-resistant human cancer cell lines: A549cisR, HeLacisR and MCF-7cisR cell lines. The possible structure–activity relationship of these compounds was studied from the effect of both alkyl groups bound with tin centers and the structure of organotin compounds on their in vitro antiproliferative activities. All complexes can interact with calf thymus DNA (CT-DNA) in the intercalation mode, as evidenced by UV-Vis absorption, luminescence and circular dichroism (CD) titrations. Furthermore, the interaction of all compounds and bovine serum albumin (BSA) in static mode was characterized by fluorescence spectroscopy methods, which were confirmed by the docking study. In addition, further studies reveal that the most active di-n-butyltin(IV) compound, inducing production of ROS, can potentially be used as anticancer drug.
57 citations
TL;DR: A series of novel pyrazolo[3,4-b]pyridine based target compounds were synthesized and 1,2,4 triazole derivatives showed promising activity and compound 10d is identified as a lead molecule.
55 citations
TL;DR: In this paper, solid state structures of five organotin(IV) hydrazone compounds were determined by elemental analysis, IR, NMR spectroscopy and for 1, 2, 3, 4 and 5 single crystal X-ray diffraction analysis.
54 citations
TL;DR: A novel Fe-catalyzed olefin hydroamination with diazo compounds for accessing hydrazones has been developed and is applicable for intramolecular reactions to construct diverse heterocycles.
51 citations
TL;DR: The existence of three fully orthogonal dynamic covalent bonds is demonstrated in solution and in functional surface architectures.
Abstract: Orthogonal dynamic covalent bonds are of interest for the construction of functional systems. The orthogonality of disulfide and hydrazone exchange under basic and acidic conditions, respectively, is well established. However, the integration of boronate esters as the third bond has failed so far because they exchanged too easily, especially under hydrazone exchange conditions. In this report, a collection of bioinspired catechols derived from adhesive natural products from cyanobacteria is screened with phenylboronic acids with proximal alcohols (benzoboroxoles), amines and fluorines to identify the least labile boronate esters. Moreover, Kool's 2-aminophenol catalysts are introduced to selectively accelerate hydrazone exchange without disturbing sufficiently inert boronate esters. Based on these results, we identified three different conditions to selectively exchange disulfides, hydrazones and boronate esters, that is to demonstrate the existence of three orthogonal dynamic covalent bonds. Moreover, their compatibility with functional systems is confirmed by successful hydrazone exchange in multicomponent surface architectures in the presence of intact boronate esters and disulfides.
TL;DR: In this paper, a multi-stimuli responsive DCDHF-hydrazone molecular switch containing a hydrazone recognition moiety is developed for the naked-eye detection of alkaline analytes in both vapour and aqueous media.
Abstract: Multi-stimuli responsive DCDHF-hydrazone molecular switch containing a hydrazone recognition moiety is developed for the naked-eye detection of alkaline analytes in both vapour and aqueous media. Mechanisms accounting for the thermochromism, pH-sensitivity and solvatochromism are proposed. DCDHF-hydrazone chromophores of different substituents introduced nanostructures with different morphologies via a re-precipitation technique. The films formulated from these nanostructures function as solid-state vapochromic sensors for probing alkaline vapours such as amines and ammonia. The sensing performance is reversible and has differential sensitivity towards a variety of amines at comparable concentrations. The structure of the hydrazone molecular switch was established spectroscopically and by single crystal X-ray crystallography.
TL;DR: It is shown that when the two bio-orthogonal functionalities (aldehyde and azide) are combined on the same QD platform, the nanocrystal can be specifically reacted with two distinct targets and with great specificity.
Abstract: We describe the synthesis of two metal-coordinating ligands that present one or two lipoic acid (LA) anchors, a hydrophilic polyethylene glycol (PEG) segment and a terminal reactive group made of an azide or an aldehyde, two functionalities with great utility in bio-orthogonal coupling techniques. These ligands were introduced onto the QD surfaces using a combination of photochemical ligation and mixed cap exchange strategy, where control over the fraction of azide and aldehyde groups per nanocrystal can be easily achieved: LA-PEG-CHO, LA-PEG-N3, and bis(LA)-PEG-CHO. We then demonstrate the application of two novel bio-orthogonal coupling strategies directly on luminescent quantum dot (QD) surfaces that use click chemistry and hydrazone ligation under catalyst-free conditions. We applied the highly efficient hydrazone ligation to couple 2-hydrozinopyridine (2-HP) to aldehyde-functionalized QDs, which produces a stable hydrazone chromophore with a well-defined optical signature. This unique optical feature...
TL;DR: In vitro cytotoxic potential of the above ruthenium hydrazone complexes assayed against the A549 cell line revealed a significant growth inhibition and cell death induced by the complexes showed noticeable changes in the cell morphology which resembled apoptosis.
Abstract: A set each of new bivalent and trivalent ruthenium complexes, [RuIII(HL)Cl2(EPh3)2] and [RuII(L)(CO)(EPh3)2] (E = P (complexes 1 and 2) or As (complexes 3 and 4)) were synthesised from the reactions of [RuIIICl3(EPh3)3] with 2-hydroxynaphthaldehyde benzoic acid hydrazone (H2L) in methanol–chloroform and characterized by elemental analysis, spectral data and XRD study. A suitable mechanism to account for the formation of bivalent ruthenium carbonyl complexes from the corresponding trivalent precursors is provided by considering the role of added base in the reaction. Interaction of complexes 1–4 with CT-DNA/bovine serum albumin was analysed with absorption and emission spectral titration studies. In vitro cytotoxic potential of the above ruthenium hydrazone complexes 1–4 assayed against the A549 cell line revealed a significant growth inhibition. The test complexes 1–4 added in IC50 concentration into the cell culture medium enhanced the release of lactate dehydrogenase, NO and reactive oxygen species in comparison with the control. Cell death induced by the complexes was studied using a propidium iodide staining assay and showed noticeable changes in the cell morphology which resembled apoptosis.
TL;DR: In this paper, the quinoline hydrazone ligands were synthesized through multi-step reactions using Vilsmeier-Haack reaction and the molecular structures of the ligands (3a, 3i) and the Zn complexes were characterized by elemental analysis and spectral studies like FT-IR, 1 H and 13 C NMR, MS, UV-Visible and fluorescence.
TL;DR: One-pot synthetic routes from fur furals to polysubstituted aromatic compounds have been developed in water, without the need for any organic solvents as discussed by the authors, where the reaction proceeds via an uncatalysed one-pot reaction cascade through formation of a hydrazone derivative, in situ cycloaddition with a dienophile, then aromatisation.
TL;DR: It is shown that when Schiff base formation between aldehydes and arylhydrazines is carried out with an appropriately positioned boron atom, then aromatic B-N heterocycles form irreversibly.
Abstract: We use kinetic data, photophysical properties, and mechanistic analyses to compare recently developed high-rate constant oxime and hydrazone formations. We show that when Schiff base formation between aldehydes and arylhydrazines is carried out with an appropriately positioned boron atom, then aromatic B–N heterocycles form irreversibly. These consist of an extended aromatic structure amenable to the tailoring of specific properties such as reaction rate and fluorescence. The reactions work best in neutral aqueous buffer and can be designed to be fluorogenic – properties which are particularly interesting in bioconjugation.
TL;DR: In this paper, 4-Acyl-pyrazole-3-carboxylic acids (1) were synthesized via the reaction of 4-acyl-2,3-furandiones (F) with hydrazone (1-benzylidene-2-(2,5-dimethyl-phenyl)-hydrazine) by heating under solid phase and their acid chlorides were obtained.
TL;DR: In this article, nine mercury(II) complexes of the composition [Hg(Ln)(X)2] (X = Cl, Br and I, n = 1-3), (L1 = 2-pyridine piconyl hydrazone); L2 = (2-acetylpyridinitriyi-piconyl hydrone) and L3 = ( 2-phenyl pyridine photo-photonic hydrazon) are synthesized and spectroscopically characterized.
Abstract: In this study, nine mercury(II) complexes of the composition [Hg(Ln)(X)2] (X = Cl, Br and I, n = 1–3), (L1 = 2-pyridine piconyl hydrazone); L2 = (2-acetylpyridine piconyl hydrazone) and L3 = (2-phenylpyridine piconyl hydrazone) are synthesized and spectroscopically characterized. Single-crystal X-ray crystallography showed that the molecular complexes can aggregate into larger entities depending upon the anion coordinated to the metal centre. Moreover, Hirshfeld surface (HS) analyses were employed to gain additional insight into interactions responsible for the packing of complexes 1–9. Quantitative examination of 2D fingerprint plots revealed, among others, the dominating participation of H⋯H and H⋯X interactions in the molecular packing. Moreover, C–H⋯X hydrogen bonds, π–π, and chelate-ring–π interactions are described and analysed by means of density functional theory (DFT) calculations since they play an important role in the construction of three-dimensional supramolecular frameworks. The influence of the halide on the energetic features of the assemblies has been also studied.
TL;DR: In this paper, a resumable Schiff-base fluorescent probe 7methoxychromone-3-carbaldehyde-(3′-hydroxy-2′-naphthaleneformyl) hydrazone (L ) was designed and synthesized for selective recognition Zn 2+.
TL;DR: In this paper, a new oxidovanadium(V) complex, [VO(L)Cl2] (1), is synthesized by the reaction of VOCl3 with (E)-N′-(phenyl(pyridin-2-yl)methylene)isonicotinhydrazide (HL) in chloroform as a solvent.
TL;DR: A novel series of sulfonamide derivatives 4-21 have been synthesized starting from the strategic starting material E)-4-Chloro-N-(4-(1-(2-cyanoacetyl)hydrazono)ethyl)phenyl) benzenesulfonamide 4 and showed higher activity compared to doxorubicin as a positive control.
TL;DR: A multicolor fluorogenic hydrazone transfer ("DarkZone") system to label alkyl aldehydes is described, yielding up to 30-fold light-up response in vitro and enabling the monitoring of cellular acetaldehyde production from ethanol over time by flow cytometry, demonstrating the utility of the DarkZone dyes for measuring and imaging the aldeHydic load related to human disease.
Abstract: Aldehydes are key intermediates in many cellular processes, from endogenous metabolic pathways like glycolysis to undesired exogenously induced processes such as lipid peroxidation and DNA interstrand cross-linking. Alkyl aldehydes are well documented to be cytotoxic, affecting the functions of DNA and protein, and their levels are tightly regulated by the oxidative enzyme ALDH2. Mutations in this enzyme are associated with cardiac damage, diseases such as Fanconi anemia (FA), and cancer. Many attempts have been made to identify and quantify the overall level of these alkyl aldehydes inside cells, yet there are few practical methods available to detect and monitor these volatile aldehydes in real time. Here, we describe a multicolor fluorogenic hydrazone transfer (“DarkZone”) system to label alkyl aldehydes, yielding up to 30-fold light-up response in vitro. A cell-permeant DarkZone dye design was applied to detect small-molecule aldehydes in the cellular environment. The new dye design also enabled the m...
16 Dec 2016
TL;DR: In this paper, four tricyanofuran disperse dyestuffs 3a-d bearing hydrazone moiety were synthesized in order to investigate their possible antibacterial activity.
Abstract: Four novel tricyanofuran disperse dyestuffs 3a-d bearing hydrazone moiety were synthesized in order to investigate their possible antibacterial activity. The hydrazone moiety was introduced via azo-coupling of the tricyanofuran with the appropriately functionalized diazonium salt. The optical properties of these compounds showed interesting solvatochromic properties. The absorption peaks are observed in the wavelength range 454-513 nm. It can also be seen that they display different maximum emissions in the wavelength range 528-615 nm. The functional groups attached to the hydrazone moiety influenced both on absorption and emission maxima. The prepared hydrazone-based disperse dyes were applied for dyeing polyester fabrics, affording satisfactory results. Furthermore, compounds 3a and 3c demonstrated a relatively strong antibacterial activity against some selected gram positive Staphylococcus aureus and Bacillus subtilis;and gram negative Escherichia coli and Pseudomonas aeuroginosa employing Ampicillin as standard drug.
TL;DR: In this paper, a series of novel thiazole compounds were synthesized via one-pot three-component reaction of aldehyde/ketone, thiosemicarbazide, and chlorinated β-keto ester catalyzed by anhydrous sodium acetate.
TL;DR: Antioxidant studies showed that the ruthenium(II) complexes have a strong radical-scavenging properties and the cytotoxic effect of the compounds examined on cancerous cell lines showed thatThe complexes exhibited substantial anticancer activity.
Abstract: Three new ruthenium(II) complexes with hydrazone ligands, furan-2-carboxylic acid (2,4-dihydroxy-benzylidene)-hydrazide (HL1), furan-2-carboxylic acid [4-(ethyl-propyl-amino)-2-hydroxy-benzylidene]-hydrazide (HL2) and furan-2-carboxylic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide (HL3) were synthesized and characterized by various spectro-analytical techniques. The hydrazone ligands act as a tridendate ligand with ONO as the donor sites and are preferably found in the enol form in all the complexes. The molecular structure of the ligands was determined by single crystal X-ray diffraction technique. The interaction of the ligands and the complexes with CT-DNA were evaluated by an absorption titration method which revealed that the compounds interact with CT-DNA through intercalation. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the calf thymus DNA hydrolytically. Antioxidant studies showed that the ruthenium(II) complexes have a strong radical-scavenging properties. Further, the cytotoxic effect of the compounds examined on cancerous cell lines showed that the complexes exhibited substantial anticancer activity.
TL;DR: The 1:1 Cu/ligand complex, C1, promotes A549 cell apoptosis possibly through the intrinsic reactive oxygen species (ROS) mediated mitochondrial pathway, accompanied by the regulation of Bcl-2 family proteins.
TL;DR: The Co(III) and Ni(II) complexes [Co(L2)2(bpy)]Cl (1) and [Ni(L 2)2 (phen)] (2) have been synthesized and characterized by infra-red, UV-Vis, ESI-MS spectroscopies and elemental analyses as mentioned in this paper.
TL;DR: In this article, a sterically encumbered hydrazone, H10C5N−N═C(C9H14) (NC5H10 = piperidine, C 9H14 = 2-adamantdiyl), was shown to react as active Lewis pairs by their specific donor-acceptor functionality and activate C-H bonds of moderately acidic substrates.
TL;DR: In this paper, the Pd(II) complexes were synthesized by using 4-hydoxy benzoic acid (5-chloro-2-hydroxy-benzylidene)-hydrazide (H 2 L) ligand and the structure of the ligand was confirmed by using analytical, spectral and single crystal X-ray diffraction techniques.