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981.
Rhodium‐Catalyzed Enantioselective Intramolecular CH Silylation for the Syntheses of Planar‐Chiral Metallocene Siloles
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Dr. Qing‐Wei Zhang Kun An Li‐Chuan Liu Yuan Yue Prof. Dr. Wei He 《Angewandte Chemie (International ed. in English)》2015,54(23):6918-6921
Reported herein is the rhodium‐catalyzed enantioselective C? H bond silylation of the cyclopentadiene rings in Fe and Ru metallocenes. Thus, in the presence of (S)‐TMS‐Segphos, the reactions took place under very mild conditions to afford metallocene‐fused siloles in good to excellent yields and with ee values of up to 97 %. During this study it was observed that the steric hindrance of chiral ligands had a profound influence on the reactivity and enantioselectivity of the reaction, and might hold the key to accomplishing conventionally challenging asymmetric C? H silylations. 相似文献
982.
Chun‐Hua Yang Yu‐Shi Zhang Wen‐Wen Fan Dr. Gong‐Qing Liu Prof. Dr. Yue‐Ming Li 《Angewandte Chemie (International ed. in English)》2015,54(43):12636-12639
A direct and catalyst‐free method for the intramolecular aminoboration of unfunctionalized olefins is reported. In the presence of BCl3 (1 equiv) as the sole boron source, intramolecular aminoboration of sulfonamide derivatives of 4‐penten‐1‐amines, 5‐hexen‐1‐amines, and 2‐allylanilines proceeded readily without the use of any catalyst. The boronic acids obtained after hydrolysis could be converted into the corresponding pinacol borates in a straightforward manner by treatment with pinacol under anhydrous conditions. 相似文献
983.
Qing He Dr. Yu‐Fei Ao Prof. Zhi‐Tang Huang Prof. De‐Xian Wang 《Angewandte Chemie (International ed. in English)》2015,54(40):11785-11790
Anion–π interactions have been widely studied as new noncovalent driving forces in supramolecular chemistry. However, self‐assembly induced by anion–π interactions is still largely unexplored. Herein we report the formation of supramolecular amphiphiles through anion–π interactions, and the subsequent formation of self‐assembled vesicles in water. With the π receptor 1 as the host and anionic amphiphiles, such as sodium dodecylsulfate (SDS), sodium laurate (SLA), and sodium methyl dodecylphosphonate (SDP), as guests, the sequential formation of host–guest supramolecular amphiphiles and self‐assembled vesicles was demonstrated by SEM, TEM, DLS, and XRD techniques. The intrinsic anion–π interactions between 1 and the anionic amphiphiles were confirmed by crystal diffraction, HRMS analysis, and DFT calculations. Furthermore, the controlled disassembly of the vesicles was promoted by competing anions, such as NO3?, Cl?, and Br?, or by changing the pH value of the medium. 相似文献
984.
985.
Dr. Junhe Ma Qing Cao Dr. Sarah M. McLeod Keith Ferguson Ning Gao Prof. Alexander L. Breeze Dr. Jun Hu 《Angewandte Chemie (International ed. in English)》2015,54(16):4764-4767
An NMR‐based approach marries the two traditional screening technologies (phenotypic and target‐based screening) to find compounds inhibiting a specific enzymatic reaction in bacterial cells. Building on a previous study in which it was demonstrated that hydrolytic decomposition of meropenem in living Escherichia coli cells carrying New Delhi metallo‐β‐lactamase subclass 1 (NDM‐1) can be monitored in real time by NMR spectroscopy, we designed a cell‐based NMR screening platform. A strong NDM‐1 inhibitor was identified with cellular IC50 of 0.51 μM , which is over 300‐fold more potent than captopril, a known NDM‐1 inhibitor. This new screening approach has great potential to be applied to targets in other cell types, such as mammalian cells, and to targets that are only stable or functionally competent in the cellular environment. 相似文献
986.
Fangyi Cheng Qing Zhao Xiaopeng Han Jun Chen 《Angewandte Chemie (International ed. in English)》2015,54(14):4338-4343
The ever‐increasing consumption of a huge quantity of lithium batteries, for example, Li–MnO2 cells, raises critical concern about their recycling. We demonstrate herein that decayed Li–MnO2 cells can be further utilized as rechargeable lithium–air cells with admitted oxygen. We further investigated the effects of lithiated manganese dioxide on the electrocatalytic properties of oxygen‐reduction and oxygen‐evolution reactions (ORR/OER). The catalytic activity was found to be correlated with the composition of LixMnO2 electrodes (0<x<1) generated in situ in aprotic Li–MnO2 cells owing to tuning of the Mn valence and electronic structure. In particular, modestly lithiated Li0.50MnO2 exhibited superior performance with enhanced round‐trip efficiency (ca. 76 %), high cycling ability (190 cycles), and high discharge capacity (10 823 mA h gcarbon?1). The results indicate that the use of depleted Li–MnO2 batteries can be prolonged by their application as rechargeable lithium–air batteries. 相似文献
987.
Development of a magnetic solid‐phase extraction coupled with high‐performance liquid chromatography method for the analysis of polyaromatic hydrocarbons
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Yan Ma Jiawen Xie Jing Jin Wei Wang Zhijian Yao Qing Zhou Aimin Li Ying Liang 《Journal of separation science》2015,38(14):2517-2525
A novel magnetic solid phase extraction coupled with high‐performance liquid chromatography method was established to analyze polyaromatic hydrocarbons in environmental water samples. The extraction conditions, including the amount of extraction agent, extraction time, pH and the surface structure of the magnetic extraction agent, were optimized. The results showed that the amount of extraction agent and extraction time significantly influenced the extraction performance. The increase in the specific surface area, the enlargement of pore size, and the reduction of particle size could enhance the extraction performance of the magnetic microsphere. The optimized magnetic extraction agent possessed a high surface area of 1311 m2/g, a large pore size of 6–9 nm, and a small particle size of 6–9 μm. The limit of detection for phenanthrene and benzo[g,h,i]perylene in the developed analysis method was 3.2 and 10.5 ng/L, respectively. When applied to river water samples, the spiked recovery of phenanthrene and benzo[g,h,i]perylene ranged from 89.5–98.6% and 82.9–89.1%, respectively. Phenanthrene was detected over a concentration range of 89–117 ng/L in three water samples withdrawn from the midstream of the Huai River, and benzo[g,h,i]perylene was below the detection limit. 相似文献
988.
Practical method for the rapid screening of xanthine oxidase inhibitors in herbal extracts by high‐performance liquid chromatography based on on‐line precolumn enzymatic reaction
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Chun‐Hua Zhou De‐Qiang Li Yuan‐Yuan Xiao Xiu‐Ling Yang Zhi‐Qing Zhang 《Journal of separation science》2015,38(13):2267-2271
A high‐performance liquid chromatography method with on‐line precolumn enzymatic reaction for the screening of xanthine oxidase inhibitors in natural extracts was developed. In this method, the enzymatic reaction occurred at the capillary inlet during a predetermined waiting period, after which the reaction product, uric acid, was separated and detected by liquid chromatography using ultraviolet absorption at 295 nm. Enzyme inhibition can be read out directly from the reduced peak area of uric acid in comparison to a reference chromatogram obtained in the absence of any inhibitor. In the present study, the availability of on‐line precolumn enzymatic reaction with ultraviolet detection was firstly evaluated by determining the inhibitory mechanism and IC50 values of allopurinol, a commercially available positive drug. Then, the newly developed method was applied to screening of ten natural extracts from traditional Chinese medicine and as a result, the extract of Epimedium sagittatum (Sieb. et Zucc.) Maxim was found to be most positive for xanthine oxidase inhibition. The results obtained were compared with those obtained by offline enzyme assay and the effectiveness of the present method was confirmed. A rapid, low‐cost, and fully automated method for xanthine oxidase inhibitor screening was proposed. 相似文献
989.
Lei Wang Man Zhang Ying‐Ying Jin Qing Lu Qi Fang 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(1):69-74
Three 1‐phenylindolin‐2‐one derivatives, namely 1‐phenylindolin‐2‐one, C14H11NO, (I), 5‐bromo‐1‐phenylindolin‐2‐one, C14H10BrNO, (II), and 5‐iodo‐1‐phenylindolin‐2‐one, C14H10INO, (III), have been synthesized and their structures determined. Compounds (I) and (II) crystallized in the centrosymmetric space groups Pbca and P21/c, respectively, while compound (III) crystallized in the polar space group Aea2. Density functional theory (DFT) calculations show that the molecular dipole moment gradually decreases in the order (I) > (II) > (III). The relatively smaller dipole moment of (III) and the larger non‐electrostatic intermolecular interactions may be the main reasons for the noncentrosymmetric and polar structure of (III). 相似文献
990.
A series of 5‐aryl‐1H‐pyrazole derivatives were synthesized via the reaction of 3‐(dimethylamino)‐1‐arylprop‐2‐en‐1‐one with hydrazine in aqueous media without using any catalyst. This method has the advantages of easier work‐up, mild reaction condition, high yields, and an environmentally benign procedure. 相似文献