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41.
42.
Reaction of 5-ethyl pyridine-2-ethanol 1 and methane sulphonyl chloride gives corresponding sulphonate 2; which on condensation with p-hydroxy benzaldehyde will give 4-[2-(5-ethylpyridin-2-yl)ethoxy]benzaldehyde 3. A series of chalcones 4a–o were prepared from 3 and substituted aromatic acetophenone. Chalcones 4a–o further react with guanidine nitrate to give a series of pyrimidines 5a–o which condense with 3,4-dichlorobenzylchloride to give amide derivatives 6a–o. Newly synthesized compounds have been examined on the basis of spectral analysis. All the compounds were screened against different gram-positive and gram-negative bacteria. Most of these compounds showed better inhibitory activity in comparison with the standard drugs. 相似文献
43.
Kashyap HK Hettige JJ Annapureddy HV Margulis CJ 《Chemical communications (Cambridge, England)》2012,48(42):5103-5105
Structural patterns that have the same spatial periodicity but a phase offset give rise to peaks and anti-peaks (negative-going peaks) at the same q value in the SAXS structure function S(q). As an example, in ionic liquids we often find charge alternation, and at the distance where one finds a density enhancement of charges of the same type one also finds a depletion of charges of opposite sign. Another such situation arises with polar-apolar densities. At distances where there is enhancement of same-type (polar-polar or apolar-apolar) densities there is also a depletion of opposite-type (polar-apolar) density. This gives rise to prepeaks and what we call same spatial periodicity anti-prepeaks. 相似文献
44.
Cognitive disorders can be associated with brain trauma, neurodegenerative disease or as a part of physiological aging. Aging in humans is generally associated with deterioration of cognitive performance and, in particular, learning and memory. Different therapeutic approaches are available to treat cognitive impairment during physiological aging and neurodegenerative or psychiatric disorders. Traditional herbal medicine and numerous plants, either directly as supplements or indirectly in the form of food, improve brain functions including memory and attention. More than a hundred herbal medicinal plants have been traditionally used for learning and memory improvement, but only a few have been tested in randomized clinical trials. Here, we will enumerate those medicinal plants that show positive effects on various cognitive functions in learning and memory clinical trials. Moreover, besides natural products that show promising effects in clinical trials, we briefly discuss medicinal plants that have promising experimental data or initial clinical data and might have potential to reach a clinical trial in the near future. 相似文献
45.
Hemant Kumar Nashine Zoran Kadelburg Stojan Radenovi? 《Applied mathematics and computation》2012,218(9):5422-5432
We establish coupled coincidence point results for mixed g-monotone mappings under general contractive conditions in partially ordered cone metric spaces over solid cones. We also present results on existence and uniqueness of coupled common fixed points. Our results generalize, extend and unify several well known comparable results in the literature. To illustrate our results and to distinguish them from the earlier ones, we equip the paper with examples. 相似文献
46.
Madhukar S. Chande C. Sajithkumar Hemant S. Mondkar Pravin A. Barve Sachin Diwan 《Journal of heterocyclic chemistry》2012,49(2):329-335
The Dieckmann condensation has been used for the first time for the syntheses of novel 1,2,4‐triazolophanes and 1,3,4‐oxadiazolophanes. The bis‐1,3,4‐oxadiazol‐2‐thiols 1a and 1b were reacted with ethyl bromoacetate to give the diesters 2a and 2b . Diesters 2a and 2b were treated under dry conditions with sodium methoxide in methanol to afford desired symmetrical 1,3,4‐oxadiazolophanes 3a and 3b . Similarly, diesters of macrocycle precursors containing 1,2,4‐triazole moiety, that is, 6a , 6b , 10 , 13a , 13b , and 13c were synthesized from 5a , 5b , 9 , 12a , 12b , and 12c , respectively. Dieckmann condensation of these diesters afforded symmetrical ketones 7a , 7b , 11 , 14a , 14b , and 14c . Extrusion of CO2 was observed after in situ hydrolysis of the conventional Dieckmann product during neutralization by dilute mineral acids to afford highly symmetrical ketone in good yields. Further, the ketones 14a , 14b , and 14c were converted into their respective thiones by the reaction with Lawesson's reagent. All the products were synthesized with good yields, and structures were confirmed by various spectroscopic tools and elemental analyses. J. Heterocyclic Chem.,, (2012). 相似文献
47.
Yun Zhu Michael Stollenz Samuel R. Zarcone Sugam Kharel Hemant Joshi Nattamai Bhuvanesh Joseph H. Reibenspies John A. Gladysz 《Chemical science》2022,13(45):13368
The diphosphine complexes cis- or trans- PtCl2(P((CH2)n)3P ) (n = b/12, c/14, d/16, e/18) are demetalated by MC X nucleophiles to give the title compounds (P((CH2)n)3)P (3b–e, 91–71%). These “empty cages” react with PdCl2 or PtCl2 sources to afford trans- MCl2(P((CH2)n)3P ). Low temperature 31P NMR spectra of 3b and c show two rapidly equilibrating species (3b, 86 : 14; 3c, 97 : 3), assigned based upon computational data to in,in (major) and out,out isomers. These interconvert by homeomorphic isomerizations, akin to turning articles of clothing inside out (3b/c: ΔH‡ 7.3/8.2 kcal mol−1, ΔS‡ −19.4/−11.8 eu, minor to major). At 150 °C, 3b, c, e epimerize to (60–51) : (40–49) mixtures of (in,in/out,out) : in,out isomers, which are separated via the bis(borane) adducts 3b, c, e·2BH3. The configurational stabilities of in,out-3b, c, e preclude phosphorus inversion in the interconversion of in,in and out,out isomers. Low temperature 31P NMR spectra of in,out-3b, c reveal degenerate in,out/out,in homeomorphic isomerizations (ΔG‡Tc 12.1, 8.5 kcal mol−1). When (in,in/out,out)-3b, c, e are crystallized, out,out isomers are obtained, despite the preference for in,in isomers in solution. The lattice structures are analyzed, and the D3 symmetry of out,out-3c enables a particularly favorable packing motif. Similarly, (in,in/out,out)-3c, e·2BH3 crystallize in out,out conformations, the former with a cycloalkane solvent guest inside.It’s not a magic trick. Molecules can turn themselves inside out, just like articles of clothing or other familiar household objects. This behavior is demonstrated for the title compounds through a combination of synthesis, rate, and NMR studies. 相似文献
48.
Dharmendra Kashyap Manushree Tanwar Chanchal Rani Pranit Hemant Bagde Siddharth Singh Nidhi Varshney Vaishali Saini Amit Mishra Rajesh Kumar Hem Chandra Jha 《Journal of Raman spectroscopy : JRS》2024,55(5):549-565
Helicobacter pylori and Epstein–Barr Virus (EBV) are Group 1 carcinogens that can enhance gastric cancer progression. Bioactive substances extracted from plants can be effective therapeutic agents in cancer treatment. For example, Withania somnifera extract-WSE reduces the Gankyrin oncoprotein, which is upregulated in the presence of H. pylori and EBV. The various biochemical and metabolic changes upon 24 hrs post-infection followed by W. somnifera extract (WSE) treatment on gastric epithelial cells (AGS) can be studied using spectroscopic techniques. In the biomedical sciences, Raman and NMR spectroscopy have been extensively employed to interpret cellular alterations contributing to the onset of infection and the severity of gastric cancer. More specifically, alterations in cellular biochemical homeostasis are linked to the moieties of cholesterol, collagen, choline, carbohydrate, lipids, tyrosine, and phenylalanine. Further, we have found significantly elevated FWHM for carbohydrates, tumor associated protein, collagen, cholesterol, and cholesterol ester in the co-infection model. We also looked into the potential correlation between these molecules using molecular network analysis and found several related factors that can be modulated through biomolecular levels. These molecules are crucial in several physiological functions, including cell division, cell proliferation, apoptosis, necrosis, cell migration, and lipid transport. Our study paves the pathway to study H. pylori and EBV co-infection in human gastric epithelial cells and the therapeutic interventions of WSE in this scenario and highlights specific biomolecular alterations, which can be focused for further mechanistic investigations. 相似文献
49.
Ph3SiSH transforms amides to thioamides and Ph3SnOH performs the reverse process, with the concomitant formation of Ph3SiOH (or Ph3SiOSiPh3) and Ph3SnSSnPh3, respectively. The chemistry is a delightful illustration of the oxophilicity of silicon compared to the thiophilicity of tin and occurs under relatively mild conditions, and for amide to thioamide transformation requires no amide activation. The chemistry is in accord with available data for Si? (S)(O), Sn? (O)(S) and C?(O)(S) bond energies. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
50.
Conner A. Hoelzel Hang Hu Charles H. Wolstenholme Basel A. Karim Kyle T. Munson Kwan Ho Jung Han Zhang Prof. Yu Liu Prof. Hemant P. Yennawar Prof. John B. Asbury Prof. Xiaosong Li Prof. Xin Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(12):4815-4822
While organic donor-acceptor (D-A) molecules are widely employed in multiple areas, the application of more D-A molecules could be limited because of an inherent polarity sensitivity that inhibits photochemical processes. Presented here is a facile chemical modification to attenuate solvent-dependent mechanisms of excited-state quenching through addition of a β-carbonyl-based polar substituent. The results reveal a mechanism wherein the β-carbonyl substituent creates a structural buffer between the donor and the surrounding solvent. Through computational and experimental analyses, it is demonstrated that the β-carbonyl simultaneously attenuates two distinct solvent-dependent quenching mechanisms. Using the β-carbonyl substituent, improvements in the photophysical properties of commonly used D-A fluorophores and their enhanced performance in biological imaging are shown. 相似文献