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131.
Almir S. Gazizov Andrey V. Smolobochkin Julia K. Voronina Alexander R. Burilov Michail A. Pudovik 《合成通讯》2013,43(10):1215-1221
1-(4,4-Diethoxybutyl)-3-alkylureas undergo intramolecular cyclization in the presence of trifluoroacetic acid and various phenols, leading to the new N-alkyl-2-arylpyrrolidine-1-carboxamides with moderate to excellent yields. It was found that these compounds undergo spontaneous solid-phase epimerization at room temperature. Advantages of the proposed approach are mild reaction conditions and no need for expensive reagents or catalysts. 相似文献
132.
Ryzhkov Fedor V. Elinson Michail N. Ryzhkova Yuliya E. Vereshchagin Anatoly N. Fakhrutdinov Artem N. Egorov Mikhail P. 《Chemistry of Heterocyclic Compounds》2021,57(6):672-678
Chemistry of Heterocyclic Compounds - Electrocatalytic cascade assembly of benzylidenebarbiturates and cyclohexane-1,3-diones in methanol in the presence of sodium bromide as mediator in an... 相似文献
133.
Fast Efficient and General PASE Approach to Medicinally Relevant 4H,5H‐Pyrano‐[4,3‐b]pyran‐5‐one and 4,6‐Dihydro‐5H‐pyrano‐[3,2‐c]pyridine‐5‐one Scaffolds 下载免费PDF全文
Michail N. Elinson Fedor V. Ryzhkov Ruslan F. Nasybullin Anatoly N. Vereshchagin Mikhail P. Egorov 《Helvetica chimica acta》2016,99(9):724-731
The general ‘on‐solvent’ PASE approach was found to be medicinally relevant for 4H,5H‐pyrano[4,3‐b]pyran‐5‐one and 4,6‐dihydro‐5H‐pyrano[3,2‐c]pyridine‐5‐one scaffolds. Ammonium acetate‐catalyzed multicomponent reaction of aldehydes and two different C–H acids in the presence of small amounts of EtOH results in fast (3 – 15 min) and efficient formation of scaffolds, promising for many diverse oriented medical applications. 相似文献
134.
Total Synthesis and Biological Evaluation of Rakicidin A and Discovery of a Simplified Bioactive Analogue 下载免费PDF全文
Dr. Michail Tsakos Dr. Lise L. Clement Dr. Eva S. Schaffert Frank N. Olsen Sebastiano Rupiani Rasmus Djurhuus Wanwan Yu Kristian M. Jacobsen Nikolaj L. Villadsen Prof. Dr. Thomas B. Poulsen 《Angewandte Chemie (International ed. in English)》2016,55(3):1030-1035
We report a concise asymmetric synthesis of rakicidin A, a macrocyclic depsipeptide that selectively inhibits the growth of hypoxic cancer cells and stem‐like leukemia cells. Key transformations include a diastereoselective organocatalytic cross‐aldol reaction to build the polyketide portion of the molecule, a highly hindered ester fragment coupling reaction, an efficient Helquist‐type Horner—Wadsworth—Emmons (HWE) macrocyclization, and a new DSC‐mediated elimination reaction to construct the sensitive APD portion of rakicidin A. We further report the preparation of a simplified structural analogue (WY1) with dramatically enhanced hypoxia‐selective activity. 相似文献
135.
Catalysis of Cascade and Multicomponent Reactions of Carbonyl Compounds and CH Acids by Electricity 下载免费PDF全文
Michail N. Elinson Anatoly N. Vereshchagin Fedor V. Ryzhkov 《Chemical record (New York, N.Y.)》2016,16(4):1950-1964
This review is concerned with modern trends in the use of electrochemically induced chain reactions in cascade and multicomponent electroorganic synthesis. The review summarizes the data on the use of electrochemically induced chain reactions in cascade and multicomponent organic synthesis, which were published mainly in the last decade. 相似文献
136.
Julia N. Blyzniuk Michail A. Semenov Anna Victorovna Shestopalova 《Structural chemistry》2016,27(1):77-89
We report results of the Monte Carlo simulations of systems containing heterodimers of biological active ligands and water molecules. The study was designed to identify the possible formation of intermolecular hydrogen bonds in such systems in order to investigate the molecular mechanisms of hetero-association of aromatic ligands in aqueous solution. The geometry optimization and the calculation of the atomic charges of free ligands were carried out at DFT/B3LYP level of theory. Monte Carlo simulations with Metropolis algorithm were used to determine the low energy conformations of heterodimers in water clusters. The analysis of the Monte Carlo simulation results allows us to describe in detail the hydration properties of all investigated heterodimers and to determine the intermolecular hydrogen bonds between the functional donor–acceptor groups for some of hetero-associates under investigation. In the case of heterodimers without intermolecular hydrogen bonds, the additional stabilization of these hetero-complexes can be explained by the formation the water bridges between donor and acceptor groups of the ligands. 相似文献
137.
The molecular dynamics (MD) simulation technique has been employed to investigate the thermodynamic properties and transport coefficients of the neat liquid dimethyl sulfoxide (DMSO). The fluid has been studied at temperatures in the range 298–353 K and at a pressure equal to 1 atm. The simulations employed a nine-site potential model, which is presented for the first time here, and all the available non-polarizable models. The performance of each model is tested using the same statistical mechanical ensemble and simulation method under the same conditions, revealing its weaknesses and strengths. Thermodynamic properties, microscopic structure and dynamic properties, such as transport coefficients, rotational and single-dipole correlation times have been calculated and compared with available experimental results. Estimations of transport coefficients from various theoretical and empirical models are tested against experimental and MD results. Translational and rotational dynamics suggest the existence of the cage effect and agree with the Stokes–Einstein–Debye relation. The dipole relaxation times calculated are discussed in terms of simple and useful approximations, such as the Glarum–Powles and Fatuzzo–Mason models. 相似文献
138.
Generalova AN Oleinikov VA Zarifullina MM Lankina EV Sizova SV Artemyev MV Zubov VP 《Journal of colloid and interface science》2011,357(2):265-272
Optical sensing polymer particles with tailored semiconductor nanocrystal (QD) loading are prepared by layer-by-layer deposition technique (LbL). Polyacrolein particles of 1.2 μm diameter are used as solid support for deposition of hydrophilic CdSe/ZnS nanocrystal/polyelectrolyte multilayers formed by electrostatic interactions. The pH-dependent fluorescence of QDs and pH-dependent conformations of polyelectrolytes, which likely passivate the surface state of nanocrystals, allow a creation of both mono- and multiplex coded polymer particles with pH-dependent fluorescence intensity. Bovine serum albumin (BSA) as outermost layer makes it possible to design the optical sensing polymer particles with reversibly responded fluorescence at pH variations. The fluorescence of such polymer particles with BSA outer layer is sensitive to copper(II) ion while the fluorescence of these particles is practically insensitive to the other divalent cations (Zn(2+), Ca(2+), Ba(2+), Co(2+), Mg(2+)). The detection limit of Cu(2+) is about 15 nM. Adaptation of LbL method to prepare QD-labeled polymer particles with enhanced complexity (e.g. several types of QDs, multiple biofunctionality) is expected to open new opportunities in biotechnological applications. 相似文献
139.
Beliatis MJ Martin NA Leming EJ Silva SR Henley SJ 《Langmuir : the ACS journal of surfaces and colloids》2011,27(3):1241-1244
A UV pulsed laser writing technique to fabricate metal nanoparticle patterns on low-cost substrates is demonstrated. We use this process to directly write nanoparticle gas sensors, which operate via quantum tunnelling of electrons at room temperature across the device. The advantages of this method are no lithography requirements, high precision nanoparticle placement, and room temperature processing in atmospheric conditions. Palladium-based nanoparticle sensors are tested for the detection of water vapor and hydrogen within controlled environmental chambers. The electrical conduction mechanism responsible for the very high sensitivity of the devices is discussed with regard to the interparticle capacitance and the tunnelling resistance. 相似文献
140.
Mathematical Notes - Numerical characteristics of identities of nonassociative algebras are considered. A series of algebras with subexponential colength growth is constructed. 相似文献