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  • Open access
  • 12 Reads
Synthesis of bis (1,4-disubstituted-1,2,3 triazoles) starting from diethyl galactarate

This communication reports the synthesis of a series of bis (1,4-disubstituted-1,2,3-triazoles) starting from the known (2,3,4,5) bis acetonide protected diethyl galactarate (1). Reduction of 1 with LiAlH4 led to dioxolane 2 (90%), which upon treatment with CBr4 gave the corresponding dibromide 3 (80%). The reaction of 3 with NaN3 in DMF afforded the key diazide 4 (95%). From diazide 4 were obtained the bis (1,4-disubstituted-1,2,3 triazoles) 5-8 via click reactions with alkyl substituted acetylenes including triphenyltinacetylene. Physical characteristics of the new compounds including selected values1H, 13C, and 119Sn NMR data are given.

  • Open access
  • 14 Reads
Site-Selective Functionalization of Common Organic Fragments

The ubiquitous presence of sp3 C−H bonds in natural feedstock makes them inexpensive, easily accessible, and attractive synthons for the preparation of common and/or complex molecular frameworks in biologically active natural products, pharmaceutics, agrochemicals, and materials. However, the inertness of these bonds due to the high bond dissociation energies and low polarity difference between the carbon and hydrogen atoms makes them challenging reaction partners. Moreover, the desired site-selectivity is often an issue in reactions with multiple analogous sp3 C−H bonds. To overcome these problems, transition metal-catalyzed C−H functionalization has been developed with the assistance of various well-designed directing groups which can coordinate to a metal center to deliver it on a targeted C−H bond through an appropriate spatial arrangement, enabling C−H activation via the formation of a cyclometalated species. However, the requirement of often additional steps for the construction of the directing groups and their subsequent removal after the desired operation severely hampers the efficacy and compatibility of the reactions. A promising solution would be the utilization of a transient ligand which can bind to the substrate and coordinate to the metal center in a reversible fashion. In this way, the directing group is installed, sp3 C−H functionalization occurs, and the directing group is then removed in situ without affecting the substrate function after the catalysis is finished. Overall, the whole process occurs in a single reaction pot. Herein, we are presenting our studies on transition metal-catalyzed transient directing group-enabled C−H functionalization reaction.

  • Open access
  • 72 Reads
New in the synthesis of practically important five-membered boracarbocycles by transmetallation of aluminacarbocycles with boron halides

The data obtained by the authors in the field of chemistry of substituted borolanes and 2,3-dihydro-1H-boroles are summarized. The authors developed a selective method for the synthesis of five-membered boracarbocycles via transmetalation of aluminacarbocycles, obtained by catalytic cycloalumination of unsaturated compounds (terminal olefins or acetylenes) with AlEt3 in the presence of Cp2ZrCl2 as a catalyst, by boron halides (BF3·Et2O, BCl3, BBr3). Some examples of the use of this approach to modify steroid compounds (in particular, to introduce a borolan fragment into them) are described in this review.

  • Open access
  • 40 Reads
Synthesis and X-ray diffraction of cyclopalladated compounds derived from imine ligands.

The synthesis of cyclometallated compounds is a rapidly evolving field of chemical research, with several articles and reviews detailing its ongoing discoveries as well as applications over time, such as their usage as active catalysts. In the majority of cases, our interest in cyclometallated systems has been linked to palladium(II) compounds involving the coordination of one metal atom per organic ligand, i.e. derivatives of variously substituted [C,N] Schiff bases. Furthermore, a wide range of metal complexes containing one or more phosphorus donor atoms has been reported due to their different electrical and steric characteristics, as well as their diverse applications. Moreover, we will describe the synthesis and characterization of
new cyclopalladated compounds derived from [C,N] with homo- P,P, and heterobidentate ligands

  • Open access
  • 19 Reads
Can the antimicrobial peptide Ctx(Ile²¹)-Ha-Ahx-Cys grafted onto nanochitosan sensitize extensively drug-resistant Mycobacterium tuberculosis?

The infectious agent Mycobacterium tuberculosis (MTB) has several defense and resistance mechanisms to be eliminated. The treatment is prolonged, which in many cases generates susceptibility to generate microbial resistance. This research aimed to study whether the antimicrobial peptide Ctx(Ile²¹)-Ha-Ahx-Cys (Ctx-SH) functionalized in nanochitosan matrices could eliminate resistant MTB. For this, a nanosystem was developed with chitosan matrices previously modified with N-acetylcysteine functionalized to Ctx-SH. Modified chitosan nanoparticles (NPQ) were obtained by ionic gelation using sodium tripolyphosphate and loaded with rifampicin. Both chitosan and NPQ modifications were analyzed for physicochemical parameters by Fourier/Raman transform infrared spectroscopy and Zeta potential. Antimicrobial activity was performed in a level 3 biosafety laboratory with strains H37Rv (standard) and CF169 (extensively drug-resistant, XDR) incubated in 7H9 broth supplemented with oleic acid, albumin, dextrose, and catalase at 37°C and 5% CO2, and read using fluorescence with 0.01% resazurin after 7 days. Insertion and mapping of NPQ into macrophages were assessed using a confocal microscope after 24 h with NPQ conjugated to fluorescein isothiocyanate. Preliminary results show that the spectroscopies corroborate the hypothesis of the functionalization of the Ctx-SH peptide to the chitosan-N-acetylcysteine system because, when comparing the three spectroscopies, a gradual increase in the intensity of several bands and the formation of captive disulfide are observed; and the Zeta potential (+30mV) confirmed high application stability. Bacterial inhibition studies revealed that rifampicin-loaded antimicrobial peptide-conjugated chitosan nanoparticles have better activity than rifampicin alone against CF169 with a minimum inhibitory concentration of <0.977 µg/mL similar to the standard strain. In addition, it was shown that NPQ would be able to enter the macrophage without causing toxicity and thus take better advantage of the activity of rifampicin. Finally, it is possible to verify that the nanobioconjugation of the Ctx-SH-N-acetylcysteine-chitosan compound is capable of enhancing the activity of obsolete drugs and/or sensitizing XDR bacteria.

  • Open access
  • 39 Reads
Efficient Multi-component synthesis of new quinolines derivatives
, , , , ,

Nitrogen heterocycles represent a large class of organic molecules widely distributed in nature, which makes them of very great importance in scientific research because of their applications in various fields. Quinoline scaffolds are an important class of nitrogen heterocyclic compounds with a wide range of biological and therapeutic activities. The syntheses of quinolines derivatives have attracted considerable attention from organic researchers

We present, in this work, the synthesis of quinoline derivative using a new multi-component reaction to access to these structures in a simple, fast and efficient way.

  • Open access
  • 31 Reads
One-Pot Synthesis of New imidazole derivatives

Imidazoles are one of the important classes of heterocyclic compounds because of their wide utility. These molecules are amphoteric which can react in both as an acid or as a base. Imidazole derivatives exhibit a wide range of biological and pharmacological activities including anti-fungal, anti-bacterial, anti-depressant, anti-cancer, and anti-viral. Due to their characteristic properties, many methodologies have been developed for constructing imidazole rings.

In this work,we present the synthesis of new Imidazole derivatives via a One-Pot reaction and using eco-friendly conditions.

  • Open access
  • 36 Reads
Facile preparation of nanostructures copper-based metal-organic framework with highly selective and sensitive luminescent sensing of THF small molecules and a study of the antibacterial activity

Ultrasound-assisted has been provided a facile novel route synthesized nanostructures of Cu2(bdc)2(bpy) compound by a sonochemical irradiation process and characterized by XRD, FT-IR, TGA, and FE-SEM analysis. Herein, we report the recognition of fluorescent Cu-based three-dimensional nanostructures MOF, [Cu2(bdc)2(bpy)], (1; H2bdc ​= ​1,4-benzene dicarboxylate; bpy ​= ​4,4ʹ-bipyridine) for greatly sensing and selective of tetrahydrofuran (THF) small molecules in water aqueous solution. 1 shows a quick exploration of excellent solvent-relative luminescent spectra by emission intensity regarding quenched direction THF small molecule by a reply of time <1 ​min. As well as, the static quenching is calculated to be 11,181 ​M−1 by the fluorescence titration experiments in low concentration of THF small molecules and with a detection limit of THF to be calculated at 0.0008 ​μM. The antibacterial activities of Cu2(bdc)2bpy (1) were tested against gram-positive and gram-negative species. The as-synthesized 1 exhibited excellent antibacterial effectiveness against Escherichia coli and Staphylococcus aureus. This project is one of the first samples of a metal-organic framework based luminescent sensor as an efficacious multipurpose fluorescence component that can utilize for selective detection of THF small molecules and antibacterial activity.

  • Open access
  • 28 Reads
Synthesis of a New class of Benzothiophenes derivatives as Potential Cholinesterase Inhibitors

Benzothiophene and its substituted derivatives represent an important heterocyclic scaffold that have been widely found in many pharmaceuticals, natural products, and material science. Some benzothiophene derivatives are used as antimitotic agents, angiogenesis inhibitors, estrogen receptor antagonists and anti-inflammatory agents to name but a few.

Many other compounds containing benzothiophene core are at various stages of development as a: CI959 an anti-inflammatory agent, B428 a urokinase inhibitor, PD144795 an endothelial cell activation inhibitor as a benzothiophene oxide, T588 a cognition enhancing agent with potential application for treating Alzheimer’s dementia.

In our efforts to contribute to the development of novel compounds that may be useful in the treatment of disorders associated with Alzheimer’s disease, we evaluated the relevance of structural features on the ChEs inhibitory activity.

Considering the interesting pharmacological profile of benzothiophenes, in the current work, we have designed and prepared new 2- and 2,3-disubstituted benzo[b]thiophenes using an intramolecular Wittig reaction as a key step of a good methodology for the efficient and general synthesis of a selected series of compounds.

  • Open access
  • 33 Reads
Synthesis of Some Novel biological active 1,2,4,-Triazole Analogues.

The efficient method we have developed for the synthesis of some novel biologically active 1,2,4-Triazole Analogues, In case several five-membered aromatic systems having three hetero atoms at the symmetrical position have been studied because of their interesting physiological properties and have broad scope towards the organic transformation. It is also well established that various derivatives of 1,2,4-triazole. This is a convenient method that proceeded under clean, non-toxic, efficient, and mild reaction conditions for synthesizing the first step as a one-pot N-substituted thioureas derivatives in acetonitrile (CH3CN). In the mechanistic pathway, benzoyl isothiocyanate is formed by the reaction of 3,5-dichlorobenzoyl chloride or 3,5-Bis (Trifluoromethyl) benzoyl chloride with ammonium thiocyanate (NH4SCN). Afterward, the benzoyl isothiocyanate reacts with aminophenols like (4-Nitro, 4-chloro, 5-Chloro, 4-methyl, and 5-Methyl) to afford the N-Aryl- N’- benzoylthioureas in high yield. To the best of our knowledge, this report describes for the convenient time a procedure focused specifically on the introduction of 1,2,4, triazoles analogs from corresponding N-aryl-N’- benzoylthioureas derivatives using hydrazine hydrate in 1,4- dioxane at 70 °C for 0.5 h to showing good reactivity with electron-donating and electron-withdrawing five-membered heterocyclic examples such as 4-chloro-phenol, 5-chloro phenol, 4-nitrophenol, 4-methylphenol, 3,5-bis(trifluoromethyl)phenyl 4-chlorophenol, 3,5-bis(trifluoromethyl)phenyl 5-chlorophenol 1,2,4,-triazole derivatives, to afford moderate to the high amount of yields.