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排序方式: 共有139条查询结果,搜索用时 15 毫秒
1.
Dr. Ranjana Bisht Dr. Mihai V. Popescu Dr. Zhen He Ameer M. Ibrahim Dr. Giacomo E. M. Crisenza Prof. Dr. Robert S. Paton Prof. Dr. David J. Procter 《Angewandte Chemie (International ed. in English)》2023,62(29):e202302418
Benzothiophenes, activated by oxidation to the corresponding S-oxides, undergo C−H/C−H-type coupling with phenols to give C4 arylation products. While an electron-withdrawing group at C3 of the benzothiophene is important, the process operates without a directing group and a metal catalyst, thus rendering it compatible with sensitive functionalities—e.g. halides and formyl groups. Quantum chemical calculations suggest a formal stepwise mechanism involving heterolytic cleavage of an aryloxysulfur species to give a π-complex of the corresponding benzothiophene and a phenoxonium cation. Subsequent addition of the phenoxonium cation to the C4 position of the benzothiophene is favored over the addition to C3; Fukui functions predict that the major regioisomer is formed at the more electron-rich position between C3 and C4. Varied selective manipulation of the benzothiophene products showcase the synthetic utility of the metal-free arylation process. 相似文献
2.
One-pot synthesis of pyrano[2,3-c]pyrazole derivatives via two or multicomponent condensation of β-ketoesters, hydrazine monohydrate/phenyl hydrazine, malononitrile, and substituted benzaldehydes is of great interest not only in synthetic chemistry but also in medicinal chemistry because of the tremendous biological activities, such as anticancer, anti-inflammatory, analgesic, antimicrobial, and enzyme inhibitory activities exhibited by pyranopyrazoles. This review provides extensive knowledge on novel synthetic methodologies of biologically active non-spiro/spiro-pyrano[2,3-c]pyrazole derivatives published recently. 相似文献
3.
Hafiz Muhammad Bilal Ameer Muhammad Faizan Ameer Kaouther Ghachem Muhammad Ali Ahsan Razaq Sami Ullah Khan Muhammad Hamza Lioua Kolsi 《印度化学会志》2022,99(6):100505
The environmental degradation, combined with the continuous depletion of the world's fossil fuel reserves, has forced the search for alternative fuels. This study was performed to investigate the performance of novel biodiesels in the CI engine. The experiments were performed at three different compressions ratios (16:1, 17:1, 18:1) and four loading conditions (25%, 50%, 75%, 100%). Different types of fuels such as jatropha biodiesel (JB), roselle biodiesel (RB), and ternary biodiesel (TB) were prepared and analyzed. The thermal performance of different fuels was analyzed in terms of brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and exhaust gas temperature (EGT). The emission characteristics such as CO2 emission, NOx emission, and smoke emission were analyzed for all types of fuels. The results of these fuels in the engine were compared with mineral diesel (MD). The BTE was increased with increasing compression ratios and loads for all types of fuels. The BSFC was increased with increasing compression ratios but decreased with increasing loads. The increase in emission of NOx was observed at higher compression ratios and loads. However, the CO2 emission was decreased at higher loads and lower compression ratio. The performance curves achieved with a 20% jatropha biodiesel blend showed results that were approximate to those obtained with pure MD. The comparative analysis between different fuels showed that JB exhibit higher thermal performance as compared to other biodiesels. Therefore, JB can be a better alternative to conventional fuel. 相似文献
4.
Vladimir V. Loza Nikolay S. Vostrikov Mansur S. Miftakhov 《Mendeleev Communications》2012,22(3):125-126
Racemic monoprotected at primary hydroxy group Corey lactones were resolved using (1S,2R,5R)-6,6-dimethyl-4-oxo-3-oxabicyclo-[3.1.0]hexan-2-ol as a chiral auxiliary reagent of hemiacylal chemotype. 相似文献
5.
Herman S. Mansur Nelício F. de Sales Alexandra A. P. Mansur 《Surface and interface analysis : SIA》2011,43(11):1423-1429
In this work is reported the preparation and characterization of 5,10,15,20‐tetraphenylporphyrin (H2TPP) films at the water‐air interfaces. The surface pressure‐area isotherms (π‐A) and UV‐Vis spectroscopy were used to investigate the effect of the spreading methods and parameters on the porphyrin monolayer formation. Also, Langmuir‐Blodgett (LB) and Langmuir‐Schaefer (LS) films were deposited onto glass substrates in order to study the conformation changes in porphyrin molecular packing. Quartz crystal microbalance (QCM) was utilized as the active solid substrate for the development of the NO2 gas sensor based on the H2TPP molecular films. The results of π‐A curves have clearly shown the significant contribution of the preparation methods and processing parameters on the conformation of porphyrin molecular films. The UV‐Vis spectroscopy results using polarized absorption dichroism have indicated different molecular packing for porphyrin films deposited by LB and LS methods, with relative tilted angles of 50° ± 5° and 35° ± 5°, respectively. Moreover, the QCM response has given strong evidence that H2TPP porphyrin molecular films have performed as NO2 chemsensor. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
6.
Irum Shahzadi Ameer F. Zahoor Azhar Rasul Nasir Rasool Zohaib Raza Shahla Faisal Bushra Parveen Shagufta Kamal Muhammad Zia-ur-Rehman Faisal M. Zahid 《Journal of heterocyclic chemistry》2020,57(7):2782-2794
Theophylline-7-acetic acid (acefylline) ( 3 ) and its derivatives are pharmacologically active compounds and generally recognized as bronchodilators for the treatment of respiratory diseases like acute asthma for over 70 years. In this article, synthesis of 2-((5-((1,3-dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-yl)thio)-N-arylacetamides ( 10a-j ) has been reported. All the synthesized derivatives ( 10a-j) were structurally verified by FT-IR, 1H NMR, 13C NMR and evaluated for their anti-cancer (using MTT assay), hemolytic and thrombolytic potential. N-(4-Chlorophenyl)-2-(5-((1,3-dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-ylthio)acetamide ( 10g ) was found to be the most active against human liver cancer cell lines (Huh7) having cell viability 53.58 ± 1.28 using 100 μg/mL concentration of compound which was further in-silico modelled to describe the possible mechanistic insights for its anti-proliferative activity. The results of hemolytic and thrombolytic activities indicated that these derivatives were less toxic and hold considerable potential as a drug candidate. 2-(5-((1,3-Dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-ylthio)-N-(2-fluorophenyl)acetamide ( 10c ) of the series was found to be least toxic with 0.1% hemolysis relative to ABTS (95.5%) as positive control. 2-(5-((1,3-Dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-ylthio)-N-(tetrahydro-2H-pyran-4-yl)acetamide ( 10j ) exhibited potent clot lysis activity (90%) as compared to negative control DMSO (0.57%). 相似文献
7.
Ameer Ghuzlaan Mahmoud M. Al Omari Khaldoun A. Al-Sou’od 《Journal of solution chemistry》2009,38(1):83-94
Guest–host interaction of prednisone (PN) with cyclodextrins (CDs) have been investigated using phase solubility diagrams
(PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and
molecular mechanical modeling (MM). Estimates of the complex formation constant (K
11) show that the tendency of PN to complex with CDs follows the order: β-CD>γ-CD>HP-β-CD>α-CD. At the same pH of 7.0, β-CD forms soluble 1:1 and insoluble 1:2 PN/CD complexes (BS-type PSDs). The thermodynamic functions for 1:1 PN/β-CD estimated at pH = 7.0 (ΔG
11o=−20.8 kJ⋅mol−1) show that complexation is driven by enthalpy (−30.7 kJ⋅mol−1) but retarded by entropy (ΔS
11o=−33.1 J⋅mol−1⋅K−1) changes. The MM modeling study indicates the formation of different isomeric 1:1 complexes with CDs. PSD, DSC, XRPD, SEM
and MM studies established the formation of inclusion complexes in solution and the solid state. 相似文献
8.
Herman S. Mansur Rodrigo L. Oréfice Zélia P. Lobato Wander L. Vasconcelos Eliane S. Mansur Lucas J. C. Machado 《Adsorption》2001,7(2):105-116
Adsorption/desorption of proteins onto a biomaterial surface plays a major role on the biocompatibility of the implanted material. By modifying the biomaterial surface with specially designed functional groups one may achieve the most specific behavior of the developed material used in a biological system. Based on that, porous gel matrixes with functionalized surfaces offer unlimited possibilities to control the protein-substrate interaction behavior. In the present work, we have functionalized the surface of porous glass with several chemical groups during the synthesis of the silica matrix. The porous glass matrixes were obtained using tetraethoxysilane (TEOS)/ethanol and functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltriethoxysilane (APTES). In vitro tests of the kinetics of protein adsorption and desorption from the gel matrix were monitored by UV-visible spectroscopy. The bioactivity of the incorporated protein was verified by in vivo experiments with adult male rats, where they presented an acute hypoglycemic peak. 相似文献
9.
10.
G. A. Zou S. Mansur S. C. Hu H. A. Aisa Kh. M. Shakhidoyatov 《Chemistry of Natural Compounds》2012,48(4):635-637
The novel pyrrole alkaloid alhagifoline A (1) together with the two known analogs pyrrolezanthine (2) and pyrrolezanthine-6-methyl ether (3) were isolated from the aerial part of Alhagi sparsifolia. Their structures were established based on spectral (HR-ESI-MS, 1 H and 13C NMR, 1 H–1 H COSY, HSQC, HMBC) data. Compounds 2 and 3 were isolated from the genus Alhagi for the first time. 相似文献