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21.
[structure: see text] The first enantioselective total synthesis of (-)-Centrolobine is described. The key reaction is the synthesis of the cis-disubstituted tetrahydropyran framework by intramolecular cyclization of the enantiopure hydroxyketone 3 with Et3SiH and TMSOTf. The stereoselective reduction of the beta-ketosulfoxide 4 is the source of chirality. Revision of the absolute configuration of (-)-Centrolobine is proposed. 相似文献
22.
Benturquia N Couderc F Sauvinet V Orset C Parrot S Bayle C Renaud B Denoroy L 《Electrophoresis》2005,26(6):1071-1079
Serotonin or 5-hydroxytryptamine (5-HT) is a major neurotransmitter in the central nervous system. In this work, a method for analyzing 5-HT in brain microdialysis samples using a commercially available capillary electrophoresis (CE) system has been developed. A pH-mediated in-capillary preconcentration of samples was performed, and after separation by capillary zone electrophoresis, native fluorescence of 5-HT was detected by a 266 nm solid-state laser. The separation conditions for the analysis of 5-HT in standard solutions and microdialysates have been optimized, and this method has been validated on both pharmacological and analytical bases. Separation of 5-HT was performed using a 80 mmol/L citrate buffer, pH 2.5, containing 20 mmol/L hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and +30 kV voltage. The detection limit was 2.5 x 10(-10) mol/L. This method allows the in vivo brain monitoring of 5-HT using a simple, accurate CE measurement in underivatized microdialysis samples. 相似文献
23.
Corminboeuf O Renaud P Schiesser CH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(7):1578-1584
The stereochemical outcome of the radical haloacetal cyclization reaction (Ueno-Stork reaction) has been examined by ab initio and other molecular orbital techniques. It was found that the stereochemistry of 5-exo- and 6-exo trig cyclizations can be accurately predicted from calculations using moderate levels of theory (UHF/6-311G** or B3LYP/6-311G**). A simplified computational procedure, easily run on a standard desktop computer, has been developed that provides excellent predictive ability for the stereochemical outcome for the reactions in question. Interestingly, a novel twist transition state has been identified for the first time in 5-exo-trig radical cyclization reactions. 相似文献
24.
25.
Jie Zhang Yuyin Wang Yun Wang Yang Bai Xin Feng Jiahua Zhu Xiaohua Lu Liwen Mu Tingzhen Ming Renaud de Richter Wei Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(64):e202201984
Methane (CH4) is a potent greenhouse gas and the second highest contributor to global warming. CH4 emissions are still growing at an alarmingly high pace. To limit global warming to 1.5 °C, one of the most effective strategies is to reduce rapidly the CH4 emissions by developing large-scale methane removal methods. The purpose of this perspective paper is threefold. (1) To highlight the technology gap dealing with low concentration CH4 (at many emission sources and in the atmosphere). (2) To analyze the challenges and prospects of solar-driven gas phase advanced oxidation processes for CH4 removal. And (3) to propose some ideas, which may help to develop solar-driven gas phase advanced oxidation processes and make them deployable at a climate significant scale. 相似文献
26.
Amarender Manchoju Renaud Zelli Gang Wang Carla Eymard Adrian Oo Mona Nemer Michel Prvost Baek Kim Yvan Guindon 《Molecules (Basel, Switzerland)》2022,27(2)
The design of novel nucleoside triphosphate (NTP) analogues bearing an all-carbon quaternary center at C2′ or C3′ is described. The construction of this all-carbon stereogenic center involves the use of an intramoleculer photoredox-catalyzed reaction. The nucleoside analogues (NA) hydroxyl functional group at C2′ was generated by diastereoselective epoxidation. In addition, highly enantioselective and diastereoselective Mukaiyama aldol reactions, diastereoselective N-glycosylations and regioselective triphosphorylation reactions were employed to synthesize the novel NTPs. Two of these compounds are inhibitors of the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2, the causal virus of COVID-19. 相似文献
27.
Stefano Carli Wouter Dekeyser Reinart Coosemans Renaud Dejarnac Michael Komm Miglena Dimitrova Jiří Adámek Petra Bílková Petr Böhm 《等离子体物理论文集》2020,60(5-6):e201900155
Mean-field plasma edge transport codes such as SOLPS-ITER heavily rely on ad-hoc radial diffusion coefficients to approximately model anomalous transport. Such coefficients are experimentally determined and vary between different machines, and also depend on the operational regime and plasma location within the same device. Therefore, to match experimental data the modeller is required to manually tune several free parameters in expensive simulations, and the code's predictive capabilities are significantly downgraded. As a solution, a new model has been developed for SOLPS-ITER, solving an additional transport equation for the turbulent kinetic energy k, derived by consistently time-averaging the Braginskii equations, and including a diffusive closure for the anomalous particle flux. This closure model relates the anomalous diffusion coefficient to the local k value. The resulting equation structure and its closure are inspired by TOKAM2D isothermal interchange turbulence simulation results. Within this model, fewer and hopefully more universal free parameters are retained, thus improving the code's predictive capabilities. The new model has been tested on a COMPASS case for which upstream plasma profiles were available. Experimental data and a reference solution, obtained by matching the profiles through manual tuning of radial diffusivities, have been used to estimate the parameters of our new transport model. A ballooned particle diffusivity profile is retrieved by the new radial transport model, thanks to the proposed interchange drive. The obtained upstream profiles qualitatively agree with the experiment and prove the new model is a promising first attempt to be further refined. 相似文献
28.
Toward the Rational Design of Galactosylated Glycoclusters That Target Pseudomonas aeruginosa Lectin A (LecA): Influence of Linker Arms That Lead to Low‐Nanomolar Multivalent Ligands
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Dr. Shuai Wang Lucie Dupin Mathieu Noël Cindy J. Carroux Dr. Louis Renaud Dr. Thomas Géhin Albert Meyer Dr. Eliane Souteyrand Dr. Jean‐Jacques Vasseur Dr. Gérard Vergoten Dr. Yann Chevolot Dr. François Morvan Dr. Sébastien Vidal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11785-11794
Anti‐infectious strategies against pathogen infections can be achieved through antiadhesive strategies by using multivalent ligands of bacterial virulence factors. LecA and LecB are lectins of Pseudomonas aeruginosa implicated in biofilm formation. A series of 27 LecA‐targeting glycoclusters have been synthesized. Nine aromatic galactose aglycons were investigated with three different linker arms that connect the central mannopyranoside core. A low‐nanomolar (Kd=19 nm , microarray) ligand with a tyrosine‐based linker arm could be identified in a structure–activity relationship study. Molecular modeling of the glycoclusters bound to the lectin tetramer was also used to rationalize the binding properties observed. 相似文献
29.
A strong electric susceptibility is measured as a function of temperature in a molecular dimer which is weakly bound by a pair of hydrogen bonds. This system is a remarkable example where the dominant term in the susceptibility is due to a vibration induced electric dipole. As a consequence, the averaged square of the dipole moment varies linearly with the temperature and the susceptibility does not follow the usual 1/T Curie law. this spectacular effect demonstrates the importance of dynamics to interpret the properties of weakly bound complexes. 相似文献
30.