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Keywords = arylazide

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8 pages, 1300 KiB  
Proceeding Paper
Theoretical Study of the Addition Reaction of Arylazides to 1,3-Dicarbonyl Compounds
by Adda Abdelghani, Halima Hadj Mokhtar, Ouda Boumaza and Abderrahmane Naous
Chem. Proc. 2023, 14(1), 60; https://doi.org/10.3390/ecsoc-27-16160 - 15 Nov 2023
Viewed by 820
Abstract
Our research focuses on the synthesis of 1,2,3-triazoles through 1,3-dipolar cycloaddition involving arylazides. The reaction demonstrates high efficiency when conducted in the presence of morpholine, resulting in 100% regioselectivity towards a single isomer. A theoretical study of this reaction can be conducted to [...] Read more.
Our research focuses on the synthesis of 1,2,3-triazoles through 1,3-dipolar cycloaddition involving arylazides. The reaction demonstrates high efficiency when conducted in the presence of morpholine, resulting in 100% regioselectivity towards a single isomer. A theoretical study of this reaction can be conducted to gain insights into its mechanism and provide valuable information for its optimization. This study involves the use of computational methods, such as density functional theory (DFT), to calculate the structures, energies, and properties of the reactants, intermediates, transition states, and products involved in the reaction. The calculations were performed using the Gaussian09 program with the B3LYP(GD3BJ)/6-31G(d,p) method. Full article
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11 pages, 961 KiB  
Article
Optimization of Critical Parameters for Carbodiimide Mediated Production of Highly Modified Chitosan
by Henrik-Alexander Christ, Yannick Bourgat and Henning Menzel
Polymers 2021, 13(16), 2702; https://doi.org/10.3390/polym13162702 - 13 Aug 2021
Cited by 12 | Viewed by 4385
Abstract
An optimization of the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and hydroxy benzotriazole mediated conjugation of the polysaccharide chitosan with functional carboxylic acids was shown. Optimal parameters that enable resource-efficient synthesis of highly functionalized chitosan were identified. In particular, use of only catalytic instead of stoichiometric amounts [...] Read more.
An optimization of the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and hydroxy benzotriazole mediated conjugation of the polysaccharide chitosan with functional carboxylic acids was shown. Optimal parameters that enable resource-efficient synthesis of highly functionalized chitosan were identified. In particular, use of only catalytic instead of stoichiometric amounts of hydroxy benzotriazole and tight control of pH in reaction mixture resulted in highly efficient incorporation of the desired moieties as side chains in chitosan. As a result, the model reactant 4-azidobenzoic acid was incorporated resulting in a degree of substitution of over 30% with very high coupling efficacy of up to 90%. Similar results were obtained with other carboxylic acids such as methacrylic acid, 3-(2-furyl) propionic acid and 3-maleimido propionic acid, highlighting the broad applicability of our findings for the functionalization of chitosan. Full article
(This article belongs to the Section Polymer Chemistry)
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18 pages, 3537 KiB  
Article
Substituent Effects on EI-MS Fragmentation Patterns of 5-Allyloxy-1-aryl-tetrazoles and 4-Allyl-1-aryl-tetrazole-5-ones; Correlation with UV-Induced Fragmentation Channels
by Alina Secrieru, Rabah Oumeddour and Maria L. S. Cristiano
Molecules 2021, 26(11), 3282; https://doi.org/10.3390/molecules26113282 - 29 May 2021
Cited by 5 | Viewed by 3724
Abstract
1,4- and 1,5-disubstituted tetrazoles possess enriched structures and versatile chemistry, representing a challenge for chemists. In the present work, we unravel the fragmentation patterns of a chemically diverse range of 5-allyloxy-1-aryl-tetrazoles and 4-allyl-1-aryl-tetrazolole-5-ones when subjected to electron impact mass spectrometry (EI-MS) and investigate [...] Read more.
1,4- and 1,5-disubstituted tetrazoles possess enriched structures and versatile chemistry, representing a challenge for chemists. In the present work, we unravel the fragmentation patterns of a chemically diverse range of 5-allyloxy-1-aryl-tetrazoles and 4-allyl-1-aryl-tetrazolole-5-ones when subjected to electron impact mass spectrometry (EI-MS) and investigate the correlation with the UV-induced fragmentation channels of the matrix-isolated tetrazole derivatives. Our results indicate that the fragmentation pathways of the selected tetrazoles in EI-MS are highly influenced by the electronic effects induced by substitution. Multiple pathways can be envisaged to explain the mechanisms of fragmentation, frequently awarding common final species, namely arylisocyanate, arylazide, arylnitrene, isocyanic acid and hydrogen azide radical cations, as well as allyl/aryl cations. The identified fragments are consistent with those found in previous investigations concerning the photochemical stability of the same class of molecules. This parallelism showcases a similarity in the behaviour of tetrazoles under EI-MS and UV-irradiation in the inert environment of cryogenic matrices of noble gases, providing efficient tools for reactivity predictions, whether for analytical ends or more in-depth studies. Theoretical calculations provide complementary information to articulate predictions of resulting products. Full article
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18 pages, 1254 KiB  
Article
The Azide-Allene Dipolar Cycloaddition: Is DFT Able to Predict Site- and Regio-Selectivity?
by Giorgio Molteni and Alessandro Ponti
Molecules 2021, 26(4), 928; https://doi.org/10.3390/molecules26040928 - 10 Feb 2021
Cited by 8 | Viewed by 3239
Abstract
The site- and regio-selectivity of thermal, uncatalysed 1,3-dipolar cycloadditions between arylazides and mono- or tetra-substituted allenes with different electronic features have been investigated by both conceptual (reactivity indices) and computational (M08-HX, ωB97X-D, and B3LYP) DFT approaches. Both approaches show that these cycloadditions follow [...] Read more.
The site- and regio-selectivity of thermal, uncatalysed 1,3-dipolar cycloadditions between arylazides and mono- or tetra-substituted allenes with different electronic features have been investigated by both conceptual (reactivity indices) and computational (M08-HX, ωB97X-D, and B3LYP) DFT approaches. Both approaches show that these cycloadditions follow a nonpolar one-step mechanism. The experimental site- and regio-selectivity of arylazides towards methoxycarbonyl- and sulfonyl-allenes as well as tetramethyl- and tetrafluoro-allenes was calculated by DFT transition state calculations, achieving semiquantitative agreement to both previous and novel experimental findings. From the mechanistic standpoint, 1H-NMR evidence of a methylene-1,2,3-triazoline intermediate reinforces the reliability of the computational scheme. Full article
(This article belongs to the Special Issue Advances in Cycloadditions: Theory, Practice, and Applications)
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16 pages, 9093 KiB  
Article
New 1,2,3-Triazole-Containing Hybrids as Antitumor Candidates: Design, Click Reaction Synthesis, DFT Calculations, and Molecular Docking Study
by Islam H. El Azab, Hamdy S. El-Sheshtawy, Rania B. Bakr and Nadia A. A. Elkanzi
Molecules 2021, 26(3), 708; https://doi.org/10.3390/molecules26030708 - 29 Jan 2021
Cited by 49 | Viewed by 5003
Abstract
In an effort to improve and achieve biologically active anticancer agents, a novel series of 1,2,3-triazole-containing hybrids were designed and efficiently synthesized via the Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction of substituted-arylazides with alkyne-functionalized pyrazole-[1,2,4]-triazole hybrids. The structure geometry of these new clicked 1,2,3-triazoles [...] Read more.
In an effort to improve and achieve biologically active anticancer agents, a novel series of 1,2,3-triazole-containing hybrids were designed and efficiently synthesized via the Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction of substituted-arylazides with alkyne-functionalized pyrazole-[1,2,4]-triazole hybrids. The structure geometry of these new clicked 1,2,3-triazoles was explored by density functional theory (DFT) using the B3LYP/6-311++G(d,p) level; also, the potential activity of the compounds for light absorption was simulated by time-dependent DFT calculations (TD-DFT). The antitumor impacts of the newly synthesized compounds were in vitro estimated to be towards the human liver cancer cell line (HepG-2), the human colon cancer cell line (HCT-116), and human breast adenocarcinoma (MCF-7). Among the tested compounds, conjugate 7 was the most potent cytotoxic candidate towards HepG-2, HCT-116, and MCF-7, with IC50 = 12.22, 14.16, and 14.64 µM, respectively, in comparison to that exhibited by the standard drug doxorubicin (IC50 = 11.21, 12.46, and 13.45 µM). Finally, a molecular docking study was conducted within the epidermal growth factor receptor (EGFR) active site to suggest possible binding modes. Hence, it could conceivably be hypothesized that analogies 7, 6, and 5 could be considered as decent lead candidate compounds for anticancer agents. Full article
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17 pages, 2034 KiB  
Article
Design, Synthesis, and Antimicrobial Activities of 1,2,3-Triazole Glycoside Clickamers
by Tamer El Malah, Hany F. Nour, Amira A. E. Satti, Bahaa A. Hemdan and Wael A. El-Sayed
Molecules 2020, 25(4), 790; https://doi.org/10.3390/molecules25040790 - 12 Feb 2020
Cited by 122 | Viewed by 7043
Abstract
Bacterial resistance remains a significant threat and a leading cause of death worldwide, despite massive attempts to control infections. In an effort to develop biologically active antibacterial and antifungal agents, six novel aryl-substituted-1,2,3-triazoles linked to carbohydrate units were synthesized through the Cu(I)-catalyzed azide-alkyne [...] Read more.
Bacterial resistance remains a significant threat and a leading cause of death worldwide, despite massive attempts to control infections. In an effort to develop biologically active antibacterial and antifungal agents, six novel aryl-substituted-1,2,3-triazoles linked to carbohydrate units were synthesized through the Cu(I)-catalyzed azide-alkyne cycloaddition CuAAC of substituted-arylazides with a selection of alkyne-functionalized sugars. The chemical structures of the new derivatives were verified using different spectroscopic techniques. The novel clicked 1,2,3-triazoles were evaluated for in vitro antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa, and the obtained results were compared with the activity of the reference antibiotic “Ampicillin”. Likewise, in vitro antifungal activity of the new 1,2,3-triazoles was investigated against Candida albicans and Aspergillus niger using “Nystatin” as a reference drug. The results of the biological evaluation pointed out that Staphylococcus aureus was more susceptible to all of the tested compounds than other examined microbes. In addition, some tested compounds exhibited promising antifungal activity. Full article
(This article belongs to the Section Bioorganic Chemistry)
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14 pages, 2733 KiB  
Article
Chitosan–Azide Nanoparticle Coating as a Degradation Barrier in Multilayered Polyelectrolyte Drug Delivery Systems
by Steffen Sydow, Armin Aniol, Christoph Hadler and Henning Menzel
Biomolecules 2019, 9(10), 573; https://doi.org/10.3390/biom9100573 - 5 Oct 2019
Cited by 19 | Viewed by 4124
Abstract
Therapeutics, proteins or drugs, can be encapsulated into multilayer systems prepared from chitosan (CS)/tripolyphosphat (TPP) nanogels and polyanions. Such multilayers can be built-up by Layer-by-Layer (LbL) deposition. For use as drug-releasing implant coating, these multilayers must meet high requirements in terms of stability. [...] Read more.
Therapeutics, proteins or drugs, can be encapsulated into multilayer systems prepared from chitosan (CS)/tripolyphosphat (TPP) nanogels and polyanions. Such multilayers can be built-up by Layer-by-Layer (LbL) deposition. For use as drug-releasing implant coating, these multilayers must meet high requirements in terms of stability. Therefore, photochemically crosslinkable chitosan arylazide (CS–Az) was synthesized and nanoparticles were generated by ionotropic gelation with TPP. The particles were characterized with regard to particle size and stability and were used to form the top-layer in multilayer films consisting of CS–TPP and three different polysaccharides as polyanions, namely alginate, chondroitin sulfate or hyaluronic acid, respectively. Subsequently, photo-crosslinking was performed by irradiation with UV light. The stability of these films was investigated under physiological conditions and the influence of the blocking layer on layer thickness was investigated by ellipsometry. Furthermore, the polyanion and the degree of acetylation (DA) of chitosan were identified as additional parameters that influence the film structure and stability. Multilayer systems blocked with the photo-crosslinked chitosan arylazide showed enhanced stability against degradation. Full article
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9 pages, 1257 KiB  
Article
A Theoretical Study of the Relationship between the Electrophilicity ω Index and Hammett Constant σp in [3+2] Cycloaddition Reactions of Aryl Azide/Alkyne Derivatives
by Hicham Ben El Ayouchia, Hafid Anane, Moulay Lahcen El Idrissi Moubtassim, Luis R. Domingo, Miguel Julve and Salah-Eddine Stiriba
Molecules 2016, 21(11), 1434; https://doi.org/10.3390/molecules21111434 - 27 Oct 2016
Cited by 12 | Viewed by 7044
Abstract
The relationship between the electrophilicity ω index and the Hammett constant σp has been studied for the [2+3] cycloaddition reactions of a series of para-substituted phenyl azides towards para-substituted phenyl alkynes. The electrophilicity ω index—a reactivity density functional theory (DFT) [...] Read more.
The relationship between the electrophilicity ω index and the Hammett constant σp has been studied for the [2+3] cycloaddition reactions of a series of para-substituted phenyl azides towards para-substituted phenyl alkynes. The electrophilicity ω index—a reactivity density functional theory (DFT) descriptor evaluated at the ground state of the molecules—shows a good linear relationship with the Hammett substituent constants σp. The theoretical scale of reactivity correctly explains the electrophilic activation/deactivation effects promoted by electron-withdrawing and electron-releasing substituents in both azide and alkyne components. Full article
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12 pages, 2330 KiB  
Article
Synthesis of Isoxazole and 1,2,3-Triazole Isoindole Derivatives via Silver- and Copper-Catalyzed 1,3-Dipolar Cycloaddition Reaction
by Mohamed Mehdi Rammah, Wafa Gati, Hasan Mtiraoui, Mohamed El Baker Rammah, Kabula Ciamala, Michael Knorr, Yoann Rousselin and Marek M. Kubicki
Molecules 2016, 21(3), 307; https://doi.org/10.3390/molecules21030307 - 4 Mar 2016
Cited by 11 | Viewed by 8263
Abstract
The CuI- or Ag2CO3-catalyzed [3+2] cycloaddition of propargyl-substituted dihydroisoindolin-1-one (3) with arylnitrile oxides 1a–d (Ar = Ph, p-MeC6H4, p-MeOC6H4, p-ClC6H4) produces in good yields [...] Read more.
The CuI- or Ag2CO3-catalyzed [3+2] cycloaddition of propargyl-substituted dihydroisoindolin-1-one (3) with arylnitrile oxides 1a–d (Ar = Ph, p-MeC6H4, p-MeOC6H4, p-ClC6H4) produces in good yields novel 3,5-disubstituted isoxazoles 4 of the ethyl-2-benzyl-3-oxo-1-((3-arylisoxazol-5yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylate type. With aryl azides 2a–d (Ar = Ph, p-MeC6H4, p-OMeC6H4, p-ClC6H4), a series of 1,4-disubstituted 1,2,3-triazoles 6 (ethyl-2-benzyl-3-oxo-1-((1-aryl-1H-1,2,3-triazol-4-yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylates) was obtained. The reactions proceed in a regioselective manner affording exclusively racemic adducts 4 and 6. Compared to the uncatalyzed cycloaddition, the yields are significantly improved in the presence of CuI as catalyst, without alteration of the selectivity. The regio- and stereochemistry of the cycloadducts has been corroborated by an X-ray diffraction study of 4a, and in the case of 6a by XH-correlation and HMBC spectra. Full article
(This article belongs to the Special Issue Coinage Metal (Copper, Silver, and Gold) Catalysis)
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