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921.
Feipeng Liu Zhe Dong Jianchun Wang Guangbin Dong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2166-2170
To show the synthetic utility of palladium/norbornene (Pd/NBE) cooperative catalysis, here we report concise syntheses of indenone‐based natural products, pauciflorol F and acredinone A, which are enabled by direct annulation between aryl iodides and unsaturated carboxylic acid anhydrides. Compared to the previous indenone‐preparation approaches, this method allows simple aryl iodides to be used as substrates with complete control of the regioselectivity. The total synthesis of acredinone A features two different Pd/NBE‐catalyzed ortho acylation reactions for constructing penta‐substituted arene cores, including the development of a new ortho acylation/ipso borylation. 相似文献
922.
Metabolite identification of the antimalarial piperaquine in vivo using liquid chromatography–high‐resolution mass spectrometry in combination with multiple data‐mining tools in tandem
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Aijuan Yang Meitong Zang Huixiang Liu Peihong Fan Jie Xing 《Biomedical chromatography : BMC》2016,30(8):1324-1330
Artemisinin‐based combination therapy is widely used for the treatment of uncomplicated Plasmodium falciparum malaria, and piperaquine (PQ) is one of important partner drugs. The pharmacokinetics of PQ is characterized by a low clearance and a large volume of distribution; however, metabolism of PQ has not been thoroughly investigated. In this work, the metabolite profiling of PQ in human and rat was studied using liquid chromatography tandem high‐resolution LTQ‐Orbitrap mass spectrometry (HRMS). The biological samples were pretreated by solid‐phase extraction. Data processes were carried out using multiple data‐mining techniques in tandem, i.e., isotope pattern filter followed by mass defect filter. A total of six metabolites (M1–M6) were identified for PQ in human (plasma and urine) and rat (plasma, urine and bile). Three reported metabolites were also found in this study, which included N‐oxidation (M1, M2) and carboxylic products (M3). The subsequent N‐oxidation of M3 resulted in a new metabolite M4 detected in urine and bile samples. A new metabolic pathway N‐dealkylation was found for PQ in human and rat, leading to two new metabolites (M5 and M6). This study demonstrated that LC‐HRMSn in combination with multiple data‐mining techniques in tandem can be a valuable analytical strategy for rapid metabolite profiling of drugs. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
923.
A rapid UPLC‐MS/MS method for the determination of oleanolic acid in rat plasma and liver tissue: application to plasma and liver pharmacokinetics
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Tian‐xue Li Chao‐sen Chu Jia‐yu Zhu Tian‐yi Yang Jie Zhang Yu‐tao Hu Xing‐hao Yang 《Biomedical chromatography : BMC》2016,30(4):520-527
A reliable high‐throughput ultra‐high performance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method was developed and validated for oleanolic acid (OA) determination in rat plasma and liver tissue using glycyrrhetic acid as the internal standard (IS). Plasma and liver homogenate samples were prepared using solid‐phase extraction. Chromatographic separation was achieved on a C18 column using an isocratic mobile phase system. The detection was performed by multiple reaction monitoring mode via positive electrospray ionization interface. The calibration curves showed good linearity (R2 > 0.9997) within the tested concentration ranges. The lower limit of quantification for plasma and liver tissue was ≤0.75 ng/mL. The intra‐ and inter‐day precision and accuracy deviations were within ±15% in plasma and liver tissue. The mean extraction recoveries ranged from 80.8 to 87.0%. In addition, the carryover, matrix effect, stability and robustness involved in the method were also validated. The method was successfully applied to the plasma and hepatic pharmacokinetics of OA after oral administration to rats. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
924.
925.
Dr. Steffen Bähring Dr. Luis Martín‐Gomis Gunnar Olsen Prof. Dr. Kent A. Nielsen Dr. Dong Sub Kim Dr. Troels Duedal Prof. Dr. Ángela Sastre‐Santos Prof. Dr. Jan O. Jeppesen Prof. Dr. Jonathan L. Sessler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1958-1967
Supramolecular polymers are a class of macromolecules stabilized by weak non‐covalent interactions. These self‐assembled aggregates typically undergo stimuli‐induced reversible assembly and disassembly. They thus hold great promise as so‐called functional materials. In this work, we present the design, synthesis, and responsive behavior of a short supramolecular oligomeric system based on two hetero‐complementary subunits. These “monomers” consist of a tetrathiafulvalene‐functionalized calix[4]pyrrole (TTF‐C[4]P) and a glycol diester‐linked bis‐2,5,7‐trinitrodicyanomethylenefluorene‐4‐carboxylate (TNDCF), respectively. We show that when mixed in organic solvents, such as CHCl3, CH2ClCH2Cl, and methylcyclohexane, supramolecular aggregation takes place to produce short oligomers stabilized by hydrogen bonding and donor–acceptor charge‐transfer (CT) interactions. The self‐associated materials were characterized by 1H NMR and UV/Vis/NIR absorption spectroscopy, as well as by concentration‐ and temperature‐dependent absorption spectroscopy and dynamic light scattering (DLS) analyses of both the monomeric and oligomerized species. The self‐associated system produced from TTF‐C[4]P and TNDCF exhibits a concentration‐dependent aggregation behavior typical of supramolecular polymers. Further support for the proposed self‐assembly came from theoretical calculations. The fluorescence emitting properties of TNDCF are quenched under conditions that promote the formation of supramolecular aggregates containing TTF‐C[4]P and TNDCF. This quenching effect has been utilized as a probe for the detection of substrates in the form of anions (i.e., chloride) and nitroaromatic explosives (i.e., 1,3,5‐trinitrobenzene). Specifically, the addition of these substrates to mixtures of TTF‐C[4]P and TNDCF produced a fluorescence “turn‐on” response. 相似文献
926.
The cheap and easily available sodium dithionite and thiourea dioxide have been used as the source of sulfonyl group in the synthesis of sulfones and sulfonamides recently.Compared with other methods for the sulfonylation reactions,the strategies using sodium dithionite or thiourea dioxide provide an alternative and complementary route to diverse sulfonyl compounds.During the reaction process,sulfur dioxide anion radical is the key intermediate,which is usually generated from a single electron transfer under suitable conditions.The advantages using sodium dithionite or thiourea dioxide in the sulfonylation reactions include mild conditions and broad substrate scope with excellent functional group compatibility.Further applications by using sodium dithionite and thiourea dioxide in organic transformations will be anticipated. 相似文献
927.
Compound 1 bearing urea and viologen groups has been designed and synthesized.It could be used as a colorimetric receptor for dicarboxylate anions due to the significant color changes of the solution upon the addition of dicarboxylates.More importantly,the color changes were related to the chain lengths of the dicarboxylates tested.UV-vis,’H NMR and HRMS studies demonstrated that receptor 1 utilized hydrogen bonds and electrostatic interactions to form 1:1 stoichiometry complexes with these anions.In addition,the generation of cation radical 1’ during the complexation process was also detected by EPR. 相似文献
928.
929.
Xiang Dong Rui Sang Qiang Wang Dr. Xiang‐Ying Tang Prof. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(50):16910-16915
930.
Synthesis and characterization of intrinsic high‐barrier polyimide derived from a novel diamine monomer containing rigid planar moiety
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Yi‐Wu Liu Jie Huang Jing‐Hua Tan Yi Zeng Qian Ding Xian‐Wei Xiang Yue‐Jun Liu Hai‐liang Zhang 《Journal of polymer science. Part A, Polymer chemistry》2017,55(14):2373-2382
A new diamine monomer containing rigid planar fluorenone moiety, 2,7‐bis(4‐aminophenyl)‐9H‐fluoren‐9‐one, was synthesized through Suzuki coupling reaction. Then it was reacted with pyromellitic dianhydride to obtain a polyimide (FOPPI) via a conventional two‐step polymerization process. The prepared FOPPI exhibits excellent barrier properties, with the oxygen transmission rate and water vapor transmission rate low to 3.2 cm3·m?2·day?1 and 2.9 g·m?2·day?1, respectively. The results of wide angle X‐ray diffractograms, positron annihilation lifetime spectroscopy, and molecular dynamics simulations reveal that the excellent barrier properties of FOPPI are mainly ascribed to the crystallinity, high chain rigidity, and low free volume, which are resulted from the rigid planar moiety. FOPPI also shows outstanding thermal stability and mechanical properties with a glass transition temperature up to 420 °C, 5% loss temperature of 607 °C, coefficient of thermal expansion of 1.28 ppm K?1, and tensile strength of 150.8 MPa. The polyimide has an attractive potential application prospect in the flexible electronics encapsulation area. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2373–2382 相似文献