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排序方式: 共有117条查询结果,搜索用时 15 毫秒
31.
ZnII‐ and AuI‐Catalyzed Regioselective Hydrative Oxidations of 3‐En‐1‐ynes with Selectfluor: Realization of 1,4‐Dioxo and 1,4‐Oxohydroxy Functionalizations
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Dr. Appaso Mahadev Jadhav Sagar Ashok Gawade Dr. Dhananjayan Vasu Dr. Ramesh B. Dateer Prof. Dr. Rai‐Shung Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):1813-1817
Catalytic 1,4‐dioxo functionalizations of 3‐en‐1‐ynes to (Z)‐ and (E)‐2‐en‐1,4‐dicarbonyl compounds are described. This regioselective difunctionalization was achieved in one‐pot operation through initial alkyne hydration followed by in situ Selectfluor oxidation. The presence of pyridine alters the reaction chemoselectivity to give 4‐hydroxy‐2‐en‐1‐carbonyl products instead. A cooperative action of pyridine and ZnII assists the hydrolysis of key oxonium intermediate. 相似文献
32.
A Soibel SS Banerjee Y Myasoedov ML Rapparort E Zeldov S Ooi T Tamegai 《Pramana》2002,58(5-6):893-898
Using a novel differential magneto-optical imaging technique we investigate the phenomenon of vortex lattice melting in crystals
of Bi2Sr2CaCu2O8 (BSCCO). The images of melting reveal complex patterns in the formation and evolution of the vortex solid-liquid interface
with varying field (H)/temperature (T). We believe that the complex melting patterns are due to a random distribution of material disorder/inhomogeneities across
the sample, which create fluctuations in the local melting temperature or field value. To study the fluctuations in the local
melting temperature/field, we have constructed maps of the melting landscape T
m(H, r), viz., the melting temperature (T
m) at a given location (r) in the sample at a given field (H). A study of these melting landscapes reveals an unexpected feature: the melting landscape is not fixed, but changes rather
dramatically with varying field and temperature along the melting line. It is concluded that the changes in both the scale
and shape of the landscape result from the competing contributions of different types of quenched disorder which have opposite
effects on the local melting transition. 相似文献
33.
Finly K. Arabbani Dhanapal Vasu Subramanian Sakthinathan Te-Wei Chiu Ming-Che Liu 《Electroanalysis》2023,35(3):e202200284
A novel electrochemical sensor on ZIF-8 nanocomposites (Ag/ZnO/ZIF-8) was developed to analyze the mercury ions (Hg2+). The ZIF-8 materials are one of the 3-dimensional porous metal-organic frameworks with highly accessible pores and great surface area. The ZIF-8 nanocomposites were prepared through simple sol-gel methods and their physio-chemical properties were characterized via different analytical analyses. As a result of cyclic voltammetry, Ag/ZnO/ZIF-8 exhibited a better electrocatalytic behavior towards the detection of mercury ions (Hg2+). Furthermore, the composite modified electrode was then inspected as a sensor for DPV detection of mercury ions. The nanocomposite sensor performed a wide linear range from 0.5 μM to 140 μM with a low detection limit of 40 nM, and high sensitivity of 56.06 μA μM−1 cm−2. Moreover, the ZIF-8 composite sensor showed a higher selectivity toward the detection of mercury ions (Hg2+). The real-time applications of the ZIF-8 composites sensor were inspected in various samples with good sensitivity. 相似文献
34.
Novel 7‐Nitro‐1‐(Piperidin‐4‐yl)‐4,5‐Dihydro‐[1,2,4] Triazolo[4,3‐a]Quinoline‐Sulphonamide Derivatives as Antimicrobial Agents: Design,Synthesis, and Bio‐Activity
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Bijivemula N. Reddy Peddiahgari Vasu Govardhana Reddy Bhoomireddy Rajendra Prasad Reddy Sirigi Reddy Sudharsan Reddy S. M. Reddy Madhvesh Pathak 《Journal of heterocyclic chemistry》2016,53(5):1416-1423
In attempt to search for more potent antimicrobial agents, a series of 7‐nitro‐1‐(piperidin‐4‐yl)‐4,5‐dihydro‐[1,2,4]triazolo[4,3‐a]quinoline‐derived sulphonamides were synthesized. Their structures were established by elemental analyses, IR, and NMR (1H and 13C) spectral data. The antibacterial activity of the obtained compounds was investigated against different Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive (Bacillus subtilis and Staphylococcus aureus) bacteria and antifungal activity against two fungal strains (Aspergillus niger and Aspergillus clavatus) using disk diffusion method at various concentrations (20, 40, 60, and 80 μg/mL). The study reveals that most of the title compounds showed significant antibacterial and fungal activity when compared with their respective standards streptomycin and griseofulvin. 相似文献
35.
Claisen condensation, the key step in constructing the pharmacophore of aryl beta-diketo acids (DKA) as integrase inhibitors, fails in certain cases of highly electron-deficient heterocycles such as purines. A general synthetic strategy to assemble the DKA motif on the purine scaffold has been accomplished. The synthetic sequence entails a palladium-catalyzed cross-coupling, a C-acylation involving a tandem addition/elimination reaction, and a novel ferric ion-catalyzed selective hydrolysis of an enolic ether in the presence of a carboxylic acid ester. 相似文献
36.
Dr. Dhananjayan Vasu Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2015,54(24):7162-7166
Two new palladium‐catalyzed reactions of aromatic sulfur compounds enabled the conversion of dibenzothiophenes into triphenylenes in four steps. This transformation of one aromatic framework into another consists of 1) 4‐chlorobutylation of the dibenzothiophene to form the corresponding sulfonium salt, 2) palladium‐catalyzed arylative ring opening of the sulfonium salt with a sodium tetraarylborate, 3) an intramolecular SN2 reaction to form a teraryl sulfonium salt, and 4) palladium‐catalyzed intramolecular C? S/C? H coupling through electrophilic palladation. Symmetrical as well as unsymmetrical triphenylenes of interest were synthesized in a tailor‐made fashion in satisfactory overall yields. 相似文献
37.
Hitesh B. JalaniAmit N. Pandya Arshi B. BaraiyaJitendra C. Kaila Dhaivat H. PandyaJayesh A. Sharma V. SudarsanamKamala K. Vasu 《Tetrahedron letters》2011,52(48):6331-6335
Herein, we report an efficient and facile synthesis of substituted 2-aminopyrroles from the reaction of enaminone-amidine adduct and various phenacyl, benzyl, or heteroalkyl halides in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in good to excellent yields. The reaction proceeds through an intramolecular 5-exo trig cyclization resulting into diversely substituted 2-aminopyrroles. 相似文献
38.
39.
Phosphoenolpyruvate (PEP)-dependent kinases are central to numerous metabolic processes and mediate the production of adenosine triphosphate (ATP) by substrate-level phosphorylation (SLP). While pyruvate kinase (PK, EC: 2.7.1.40), the final enzyme of the glycolytic pathway is critical in the anaerobic synthesis of ATP from ADP, pyruvate phosphate dikinase (PPDK, EC: 2.7.9.1), and phosphoenolpyruvate synthase (PEPS, EC: 2.7.9.2) help generate ATP from AMP coupled to PEP as a substrate. Here we demonstrate an inexpensive and effective electrophoretic technology to determine the activities of these enzymes by blue-native polyacrylamide gel electrophoresis (BN-PAGE). The generation of pyruvate is linked to exogenous lactate dehydrogenase (LDH), and the oxidation of reduced nicotinamide adenine dinucleotide (NADH) coupled to 2,6-dichloroindophenol (DCIP) and iodonitrotetrazolium chloride (INT) results in a formazan precipitate which is easily quantifiable. The selectivity of the enzymes is ensured by including either AMP or ADP and pyrophosphate (PP(i) ) or inorganic phosphate (P(i) ). Activity bands were readily obtained after incubation in the respective reaction mixtures for 20-30 min. Cell-free extract concentrations as low as 20 μg protein equivalent yielded activity bands and substrate levels were manipulated to optimize sensitivity of this analytical technique. High-pressure liquid chromatography (HPLC), two-dimensional (2-D) SDS-PAGE (where SDS is sodium dodecyl sulfate), and immunoblot studies of the excised activity band help further characterize these PEP-dependent kinases. Furthermore, these enzymes were readily identified on the same gel by incubating it sequentially in the respective reaction mixtures. This technique provides a facile method to elucidate these kinases in biological systems. 相似文献
40.
The chemical composition of the steam volatile oil of the whole aerial part of Scutellaria grossa Wall ex Benth. (Lamiaceae), obtained by steam distillation, has been analysed by capillary GC and GC-MS. The oil was found to be rich in oxygenated monoterpenes (88.6%). A total of 50 constituents were identified, representing 94.4% of the total oil composition. Linalool (37.0%) and 1-octen-3-ol (32.0%) were found to be the principal constituents. The antibacterial activity of the oil was determined against 10 bacterial strains by measuring the growth inhibitory zones. The oil showed significant antibacterial activity against Gram-positive bacteria, Bacillus subtilis and Enterococcus faecalis, and the Gram-negative, Klebsiella pneumoniae and Salmonella enterica enterica. A minimum inhibitory concentration of 31.25?μL mL(-1) was observed against E. faecalis. 相似文献