Publications by authors named "Davi F Back"

The development of coordination compounds with antineoplastic therapeutic properties is currently focused on non-covalent interactions with deoxyribonucleic acid (DNA). Additionally, the interaction profiles of these compounds with globular plasma proteins, particularly serum albumin, warrant thorough evaluation. In this study, we report on the interactions between biomolecules and complexes featuring hydrazone-type imine ligands coordinated with vanadium.

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We describe here the synthesis of isoselenochromenes via a nucleophilic selenocyclization reaction of benzodiynes with sodium selenide. The central parameters that affect this cyclization reaction were studied, and the best reaction conditions were applied to different substrates to determine the scope of the method. The results indicated that isoselenochromenes were obtained in higher yields when the reactions were performed by the addition of NaBH (3 equiv), at room temperature, under nitrogen atmosphere, to a solution of elemental selenium (2 equiv) in dimethylformamide (2 mL).

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An efficient and controlled site-selective annulation of 3,5-diethoxycarbonyl 4-hydrazonyl pyrazoles is described. The relative proportion of the products is affected by hydrazone intermediate configuration, reaction temperature, and Lewis acid employed. At a temperature of 110-120 °C, the reaction preferentially afforded 1-pyrazolo[3,4-]pyridazin-7(6)-ones, whereas using Yb(OTf) in MeCN reflux, 2-pyrazolo[3,4-]pyridazin-7(6)-ones were favored.

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In this work three Ni complexes with general formula [NiCl(PhP-N(R)-PPh)], R = 2-CHPy (Py = pyridine) - 1, CHPh (Ph = phenyl) - 2 and p-tol (p-tol = p-tolyl) - 3, were synthesized and characterized. These complexes were obtained in high yield by the reaction of NiCl.6HO and the corresponding diphenylphosphinoamine ligand (PhP-N(R)-PPh) in CHCl/MeOH (1:1) solution, at room temperature (∼25 °C), and characterized by H and P {H} NMR, vibrational spectroscopy in the infrared region, electronic spectroscopy in the UV-Vis regions, elemental analysis (%C, %H, %N) and single-crystal X-ray diffraction.

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Antibiotic resistance associated with pulmonary infection agents has become a public health problem, being considered one of the main priorities for immediate resolution. Thus, to increase the therapeutic options in the fight against resistant microorganisms, the synthesis of molecules from pre-existing drugs has shown to be a promising alternative. In this sense, the present work reports the synthesis, characterization, and biological evaluation (against fungal and bacterial agents that cause lung infections) of potential metallodrugs based on sulfamethoxazole complexed with Au, Ag, Hg, Cd, Ni, and Cu.

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With the increasing development of metallopharmaceuticals, coordination compounds become viable alternatives for therapeutic uses. Despite the importance of platinum derivatives in this area, first-row transition metals complexes are welcome due to their characteristics. Vanadium is a promising metal in this context, as it has a range of compounds with different biological applications, including anticancer therapeutic effects.

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A method for the synthesis of 4-organoselanyl oxazinoindolone derivatives by the cascade cyclization of N-(alkoxycarbonyl)-2-alkynylindoles using iron(III) chloride and diorganyl diselenides as promoters was developed. This protocol was applied to a series of N-(alkoxycarbonyl)-2-alkynylindoles containing different substituents. The reaction conditions also tolerated a variety of diorganyl diselenides having both electron donating and electron withdrawing groups.

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Base-promoted cyclization of 3-organoselenyl-methylene-2-alkynyl aryl propargyl ethers has been developed for the synthesis of 3-butylselanyl-methylene benzofurans, 3-methyl-2-alkynyl-benzofurans, and 4-iodo-benzo[]furan-fused selenopyrans. Under potassium -butoxide as the base and tetrahydrofuran as the solvent, at room temperature, 3-organoselenyl-methylene-2-alkynyl aryl propargyl ethers were converted into 3-butylselanyl-methylene benzofurans via a 5--dig mode. Using the same substrate, changing the solvent to dimethylsulfoxide, 3-methyl-2-alkynyl-benzofurans were selectively obtained in good yields.

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This study describes the reaction of 2-amino arylalkynyl ketones with organoselenolates to form ()-vinyl selenides, which lead to 4-organoselenyl quinolines via an intramolecular condensation. Using the optimized reaction conditions, the generality of this cyclization was studied with various arylalkynyl ketones and diorganyl diselenides. The study of the reaction mechanisms led to the isolation and identification of a vinyl selenide, which was the key intermediate for this cyclization.

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Helical complexes composed of organic ligand strands and metallic centers, called helicates, present interactions with biomacromolecules, such as deoxyribonucleic acid, as one of their main biological applications in bioinorganic chemistry. Despite the potential antineoplastic and antibacterial results of the interactions between helicates and biomacromolecules, there is still a gap of research in the literature, primarily in terms of solubility in aqueous media. In this study, we present the synthesis, structural analysis, and interaction with biomacromolecules of two water-soluble cobalt(II) double-stranded helicates: [CoL][Co(NCS)]∙9HO (C1) and [CoL]Cl∙11HO (C2).

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Organoselenyl iodide promoted the intramolecular nucleophilic cyclization of -alkynyl ethylcarbamates in the synthesis of 4-(organoselenyl) oxazolones. The reaction was regioselective, giving the five-membered oxazolone products as the unique regioisomer an initial activation of the carbon-carbon triple bond through a seleniranium intermediate, followed by an intramolecular 5- cyclization mode. The generality of the methodology has been proven by applying the optimized reaction conditions to different organoselenyl iodides and -alkynyl ethylcarbamates having different substituents directly bonded to the nitrogen atom and in the terminal position of the alkyne.

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The selective synthesis of 4-alkynyloxazolones and their further applications as substrates to electrophile-promoted nucleophilic cyclization have been developed. The reaction of ynamides with terminal alkynes proceeded smoothly to give 4-alkynyloxazolones in the presence of a catalytic amount of palladium(II) acetate. The products were obtained with the sequential formation of new C-C and C-O bonds via a cascade procedure.

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A range of bis-triazolylchalcogenium-BTD was synthesized by a copper-catalyzed azide-alkyne cycloaddition of azido arylchalcogenides and 4,7-diethynylbenzo[][1,2,5]thiadiazole . Eight new compounds were obtained in moderate to good yields using 1 mol % of copper(II) acetate monohydrate under mild reaction conditions. In addition, the synthesized bis-triazolylchalcogenium-BTD - were investigated regarding their photophysical, electrochemical, and biomolecule binding properties in solution.

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Microbial infections caused by sessile microorganisms are known to be a more challenging issue than infections caused by the same microorganisms in the planktonic state. is an opportunistic pathogen and biofilm-forming agent. This species presents intense cellular communication mediated by signaling molecules.

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This article deals with the synthesis of Schiff-based bis-azomethine-based ligands derived from pyridoxal and aliphatic dihydrazides and the synthesis of nickel(II) complexes C1-C4. The synthesized complexes had their structures elucidated by monocrystal X-ray diffraction and were characterized by vibrational and absorption spectroscopy. The synthesized ligands have characteristics that allow the formation of self-assembly processes, thus, the flexibility or rigidity of the coordination of organic molecules added to the orbitals of the Ni cation leads to the formation of helical complexes with double helix and a dinucler nickel(II) complex.

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We report here our results on the application of ynamides as substrates in the reactions with diorganyl dichalcogenides and iron(III) chloride to give selectively three different types of compounds: -α-chloro-β-(organoselenyl)enamides, 4-(organochalcogenyl)oxazolones, and vinyl tosylates. The results reveal that the selectivity in the formation of products was obtained by controlling the functional groups directly bonded to the nitrogen atom of the ynamides. Thus, α-chloro-β-(organoselenyl) enamide derivatives were exclusively obtained when the Ts- and Ms-ynamides were treated with a mixture of diorganyl diselenides (1.

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A new one-pot two-step sequential methodology for synthesis of novel 3-carboxyethyl 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives is reported. One-pot transformation of β-enamino diketones and arylhydrazines generated 4-iminium-N-arylpyrazole salt intermediates in situ, which were easily transformed into 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives by NaBHCN. The products could be isolated in the free or hydrochloride salt forms.

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Complexes with general formula [RuCl(η6-p-cymene)(P-NR-P)]X (R = CH2Py (Py = pyridine) - [1a]+, CH2Ph (Ph = phenyl) - [1b]+, Ph - [1c] and p-tol (p-tol = p-tolyl) - [1d]+; X = PF6- or BF4-) were evaluated as cytotoxic agents against two cancer cell lines (HeLa and MDA-MB-231). All metal complexes are active in the range of concentrations tested (up to 100 μmol L-1). The IC50 (μmol L-1) values for the metal complexes are lower than that found for cisplatin.

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The inflammatory response is the reaction of living tissue to an injury of a foreign nature, such as infection and irritants, and occurs as part of the body's natural defence response. Compounds capable of inhibiting cyclooxygenase (COX) enzymes, especially COX-2, have great potential as anti-inflammatory agents. Herein we present the regioselective synthesis of 49 novel compounds based on the 2-pyridone nucleus.

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We report here the regioselective 6--dig cyclization of [2-(butylselanyl)phenyl]propynols promoted by the cooperative action between diorganyl diselenides and iron(III) chloride leading to the formation of 4-methylene-3-(organoselanyl)-selenochromenes. The results of the reaction condition optimization studies showed that the solvent, the iron source, and the amount of diorganyl diselenide had a fundamental influence on the reaction yields. In the presence of iron(III) chloride (1.

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This paper describes a selenium-promoted electrophilic cyclization of arylpropiolamides allowing the synthesis of 3-organoselenyl spiro[4,5]trienones via a 5-endo-dig ipso-mode. The 3-organoselenyl-quinolinone derivative formation via 6-endo-dig was avoided using an electrophilic organoselenium species in a metal-free protocol. The use of phenylselenyl bromide (1.

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A simple and efficient methodology for highly regioselective synthesis of azomethine pyrazoles and isoxazoles containing a trifluoromethyl group is reported. The cyclocondensation of trifluoromethylated β-enamino diketones (TBED) with phenylhydrazine and hydroxylamine hydrochloride, in the presence of BF3, provided 5-aryl-4-[(tert-butyl)iminomethyl]-3-trifluoromethylazoles by aza-Michael-type 1,2-addition. The scope of the reaction was expanded by transimination with arylamines in a one-pot method starting from TBED.

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This work presents the synthesis, characterization of copper(II) complexes (C1-C6) and the potential of these compounds to mimic the catalytic activity of the enzyme superoxide dismutase (SOD). The copper(II)complexes were obtained by reaction between the aldol condensation between substituted aromatic hydrazides and aromatic aldehydes (salicylic aldehyde and pyridoxal hydrochloride), forming two new ligands (L1 to L6), resulting in new dimeric dicopper (II) complexes (C1 and C2), new three monomeric Cu derivatives (C3, C4 and C6) and a polymeric complex (C5). The Cu complexes were fully characterized by X-ray diffraction, spectroscopic and electrochemical analysis.

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A practical synthetic approach to the synthesis of 3-(organoselenyl)-imidazothiazines was developed. The methodology involved the regioselective 6-endo-dig cyclization of thiopropargyl benzimidazoles promoted by diorganyl diselenides and iron(III) chloride. The investigation to determine the best reaction conditions indicated the use of thiopropargyl benzimidazoles (0.

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The present study reports the biological evaluation of vanadium(V) complexes (1-3) against three different proteins: tyrosinase, acetylcholinesterase (AChE), and human serum albumin (HSA), which were studied by spectroscopic techniques and molecular docking. Despite the synthesis and characterization of complexes 1 and 2 having already previously described, complex 3 is a novel dioxidovanadium(V) derivative. Complex 1 can activate both tyrosinase and AChE enzymes in about 11.

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