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- Volume 20, Issue 2, 2023
Letters in Organic Chemistry - Volume 20, Issue 2, 2023
Volume 20, Issue 2, 2023
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Investigation of the Correlation between Geometrical Relationship and the Anomeric effect on Conformational Reactivities and Analyze the 1, 4-elimination
Authors: Azin Maknali, Neda Hasanzadeh and Amir BahramiAb initio molecular orbital hybrid density functional theory (B3LYP/6-311++G**) based methods and natural bond orbital (NBO) interpretation were used to investigate the 1, 4-eliminations and the correlations between the global hardness, global electronegativity, anomeric effect, thermodynamic parameters of 3-chloro-8-methyl-8-azabicyclo[3.2.1]octane (1), 3-chloro-8-methyl-8-phosphabicyclo- [3.2.1]octane (2) and 3-chloro-8-methyl-8-arsabicyclo [3.2.1]octane (3). The calculated global electronegativity (χ) differences between the axial- and equatorial-stereoisomers (Δ [χ (eq) - χ (ax)]) decreased from compound 1 to compound 3. This fact justifies that with the increase of the Lewis acid from the equatorial-stereoisomers of compound 1 to compound 3, the energy difference between the axial- and equatorial-stereoisomers decreases. NBO results showed that the anomeric effect benefits the equatorial stereoisomers. The reactions shown in this work are illustrative of the power of the anomeric effect and the geometrical relationship of the participating bonds. If the rC-Cl bond is axial, the 1, 4-elimination is avoided altogether. Whereas, if the rC-Cl bond is equatorial, the 1, 4-elimination is performed. These eliminations are rendered possible by the antiperiplanar relationship of the breaking central rC-C bond with the electron pair orbital on the heteroatom and the rC-X bond, X being a leaving group such as a halogen.
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The Nonlinear Optical Properties of Ferrocene-containing Metalloporphyrins Toward the Pico-second Laser
Authors: Yue Wang, Fengqi Guo, Xuewei Huang, Xiaodie Qian, Yinjie Lu and Zongwei ChenBackground: The nonlinear optical properties of ferrocene-containing metalloporphyrins toward pico-second laser were studied using calculational and experimental methods, and the relationship between their structures and nonlinear absorption properties were discussed. Aims: The metal ions introduced into the porphyrin rings intensively affect the nonlinear optical properties. Methods: The nonlinear optical properties and the relationship between the property and the structure of the synthesized ferrocene-containing metalloporphyrins are studied using the calculational method and the open-aperture Z-scan technology for pico-second laser. Results: The Z-scan results show that Co-P-Fc, Zn-P-Fc and Pd-P-Fc exhibit reverse saturable absorption characteristics toward the laser with 532 nm wavelength and 21 ps pulse width, and the nonlinear absorption coefficients (β) of them were 4.1, 3.2 and 1.3 cm/GW, respectively, when the incident laser fluency at the focal point of the lens is 29 mJ/cm2. In addition, the values of β decrease with the increase of the incident laser fluency. These results indicate that the nonlinear absorption characteristics of Co-P-Fc, Zn-P-Fc and Pd-P-Fc are ascribed to the excited state absorption (ESA). However, Cu-PFc, Ni-P-Fc and P-Fc show saturated absorption characteristics toward the ps laser pulse. Conclusion: To elucidate the intrinsic factors that influence the nonlinear optical properties, the electronic distribution, flow of charge density during the transition from the ground state to the excited state, and the first-order hyperpolarizability values (β) are calculated using the time-dependent density functional theory (TD-DFT). The calculated results show that the molecular polarity and the change of the molecular polarity before and after the transition from HOMO to LUMO, which is dominated by the redox potentials of the introduced metal ions, are the most important factors that affect the nonlinear optical properties of the title compounds.
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Efficient Synthesis of the Key Intermediate of Scopolamine by [4+3] Cycloaddition Reaction
Authors: Xiuyuan Duan, Qian Wang, Muhammad Shahab, Chaoqun Liang, Gudong Li and Guojun ZhengScopolamine, as an anticholinergic agent, plays a regulatory role in the peripheral nervous system. In this paper, 6,7-dehydrotropinone, which is the key intermediate of scopolamine, is synthesized in moderate yield through [4+3] cyclization reaction and Barton deoxygenation reaction. This route has good application prospects with mild reaction conditions, moderate yield, and simple operating procedures.
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Hydrazides and Hydrazones: Robust Scaffolds in Neurological and Neurodegenerative Disorders
Authors: Neetu Agrawal, Raghav Mishra, Shilpi Pathak, Ahsas Goyal and Kamal ShahBackground: Hydrazides and hydrazones are found in a variety of bioactive compounds that have a wide range of pharmacological applications. There have been significant advancements in this field in recent years, with many new aspects of hydrazone chemistry and applications emerging. Methods: This piqued researchers' interest in synthesizing a variety of hydrazone derivatives for various biological applications. Results: According to a comprehensive review of the literature, the hydrazone template possesses an immense potential to be developed for the treatment of a variety of brain-related disorders. Thus, researchers are expeditiously exploring the chemical compounds bearing hydrazone moiety to find lead molecules for the development of potential agents for the treatment of neurological and neurodegenerative disorders. Conclusion: In this review, the biological activities of various hydrazide and hydrazone analogues against various neurological and neurodegenerative disorders are summarized. Furthermore, there is a great potential for this scaffold, which medicinal chemists should look into for the development of new prospective drug candidates.
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Design and Metal-Free Synthesis and Cytotoxicity Evaluation of 5Hchromeno[ 4,3-b]pyridine Derivatives as Anti-Proliferative Agents
Background: A novel metal-free approach is reported for the synthesis of 5Hchromeno[ 4,3-b]pyridine derivatives. Indeed, chromene derivatives are found to exhibit a broad spectrum of biological activities such as antibacterial, antirhinovirus, antioxidant, cytotoxic, anticancer, and antimicrobial properties. Methods: This method provides easy access to a large number of 5H-chromeno[4,3-b]pyridine scaffolds by the condensation of 3-formylchromene with β-enaminoesters under thermal conditions. All compounds are well characterized by NMR, IR, and mass spectrometry. This is a safe and convenient protocol. Results: Thus, newly synthesized compounds are evaluated for their cytotoxicity against four human cancer cell lines, such as B16 (Skin cancer), DU145 (Prostate cancer), Hela (Cervical cancer), and CHO (Chinese hamster ovary). Conclusion: Among them, compounds 3n and 3o show an excellent anti-proliferation activity against CHO (IC50 12.33+1.13 μM), Hela (IC50 22.33+0.51 μM), and B16 (IC50 27.61+0.8 μM) cell lines, while compounds 3c, 3g, and 3q exhibit promising anti-proliferation against above four human cancer cell lines with IC50 14.96+1.9, 15.59+0.9, 13.8+0.06 μM, respectively, compared with a standard drug Doxorubicin & Mitomycin.
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Fe Doped Ga2O3 Nanomaterial Catalysed Green and Efficient One Pot Three Component Synthesis of Tetrahydrobenzo[b]pyran
Authors: Amol R. Parhad, Dilip S. Aute, Anil G. Gadhave and Bhagwat K. UphadeThe present work reports the hydrothermal synthesis of Fe doped gallium oxide nanoparticles and its characterization by IR, XRD, SEM, and EDX techniques. The characterization of Fe doped gallium oxide nanomaterial reveals the 18.58 nm particle size with monoclinic phase. The catalytic activity of nanomaterial was efficiently assessed for one-pot domino Knoevenagel and Michael's addition of different aldehydes, dimedone, and malononitriles to give tetrahydrobenzo [b] pyran derivatives. The remarkable features associated with this green protocol are good to excellent product yields (60-94%), non-chromatographic purification of product, shorter reaction time, and easy work up. The reusability and non-toxic nature of this nanomaterial catalyst escalate the importance of this work.
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Ru Nanoparticle Intercalated Montmorillonite Clay Catalytic System for the Reduction of Aliphatic/Aromatic Nitro Compounds
Authors: Om Prakash, Bhawana Jangir and Vivek SrivastavaThe Ru exchanged MMT clay was synthesized with different Ru metal stacking using the wet impregnation method. All the developed materials were analyzed with advanced analytical techniques. All the data were found in good agreement with each other. Furthermore, all the catalysts were tested for the reduction of aromatic and aliphatic nitro compounds to the corresponding amines in conventional and ionic liquid reaction mediums. The amines were easily isolated with simple ether washing in ionic liquid medium, and the catalyst was recycled up to 8 times. Various amines were also synthesized using the proposed methodology, having direct importance as building blocks of several biologically active compounds.
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Efficient Synthesis of 4-Arylmethylene-3-methylisoxazol-5(4H)-one Derivatives Catalyzed by Malic Acid
Authors: Sayed Z. Tahmasabi, Hamzeh Kiyani and Heshmat Allah SamimiThe efficient, straightforward, and green procedure was established in the direction of synthesis of 4-arylmethylene-3-methylisoxazol-5(4H)-one derivatives using the malic acid, which acted as the catalyst for the three-component heterocyclization reaction. In this reaction, aryl/heteroaryl aldehydes, hydroxylamine hydrochloride, and ethyl acetoacetate/ethyl benzoylacetate were applied as the reactants. The reaction was optimized to attain the best conditions for the synthesis of target heterocyclic compounds in a single step route. The best results were obtained from optimization experiments using 10 mol% malic acid as the catalyst, water solvent, and 50ºC temperature. The noticeable features of this process are the simplicity of the experimental procedure, the easy separation of the pure compounds from the product mixture, the simplicity of operation, avoidance of any hazardous organic solvents, no use of chromatographic purification techniques, clean reaction profiles, high yields, relatively short reaction time, and eco-friendliness.
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Novel Persian Gulf Aminated Alginate Derivatives from Sargassum Bovaneum: Synthesis and Characterization
Aims: The aim of the study was to extract and characterize alginate from a new source, conduct synthesis and characterization of novel aminated alginate derivatives, make a comparison of physicochemical properties of extracted sodium alginate with its aminated derivatives, and investigate the effect of diamines chain length on physicochemical properties of newly synthesized derivatives. Background: Alginate is a natural biopolymer found in marine brown seaweeds. Alginate is widely used in the industry due to its features, such as gelling ability, biocompatibility, biodegradability, hydrophilicity, and non-toxicity. Alginate has two types of functional groups, free hydroxyl and carboxyl groups, which can be modified. Methods: In this study, sodium alginate was extracted from sargassum boveanum in basic media and characterized by physical and spectral properties. In order to prepare alginate precursors with clickable groups for hydrogel cross-linking application, extracted sodium alginate was further treated with two different diamines, diaminoheptane (DAH) and diaminopropane (DAP), in the presence of 1-ethyl-3- (3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to form amide linkages on the alginate backbone and synthesise aminated derivatives. The products were characterized by techniques, such as FTIR, 1HNMR, TGA, XRD, and elemental analysis. Results: The average molar weight and the intrinsic viscosity of alginate from Sargassum bovaneum with a yield of 24.38% were 41.53 kDa and 0.9 dL/g 105 cps (2.5% C). Results showed that as the alginate concentration increased, the flow rate decreased with a mild slope. Conclusion: Elemental analysis (CHNS) of alginate derivatives indicated the percent of amine groups to be increased after amination reaction in comparison to corresponding alginates. The thermal analysis results indicate that the thermal stability of the sodium alginate is better than graft copolymers. Synthetic derivatives showed no particular sensitivity to environmental stimuli, such as temperature and pH changes.
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A Convergent Approach for Protected (+)-Paecilomycin F
Authors: Ravi Gurram and Srihari PabbarajaBackground: A stereoselective synthetic strategy toward (+)-paecilomycin F is reported. The approach utilizes readily available commercial 2,4,6-trihydroxy benzoic acid and easily accessible chiral R(+)-propylene oxide as starting materials. Methods: The synthesis involves regioselective Grignard reaction, Wittig reaction, Sharpless asymmetric dihydroxylation, Barbier-type allylation, Stille-coupling and ring-closing metathesis as key reactions. Results: The target molecule is produced in a 7-step linear sequence with an overall yield of 20% starting from 2,4,6-trihydroxy benzoic acid or a 12-step sequence with an overall yield of 12.95% starting from R(+)-propylene oxide. Conclusion: The aromatic fragment synthesis was achieved using earlier known protocols starting from 2,4,6-trihydroxy benzoic acid (vide infra).
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Volumes & issues
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Volume 21 (2024)
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Volume 20 (2023)
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Volume 19 (2022)
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Volume 18 (2021)
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Volume 17 (2020)
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Volume 16 (2019)
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Volume 15 (2018)
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Volume 14 (2017)
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Volume 13 (2016)
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Volume 12 (2015)
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Volume 11 (2014)
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Volume 10 (2013)
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Volume 9 (2012)
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Volume 8 (2011)
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Volume 7 (2010)
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Volume 6 (2009)
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Volume 5 (2008)
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Volume 4 (2007)
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Volume 3 (2006)
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Volume 2 (2005)
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Volume 1 (2004)