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51.
Boris A. Trofimov Anton V. Stepanov Anastasiya G. Mal’kina Ol’ga G. Volostnykh Olesya A. Shemyakina Igor’ A. Ushakov 《合成通讯》2013,43(23):2718-2729
A one-pot linkage between furan and 3(2H)-furanone rings has been effected via the microwave-assisted Et3N-catalyzed domino condensation of the furan and benzofuran carboxylic acids with available cyanopropargylic alcohols (MeCN, 100 °C, 1.2 atm, 2–17 h). Despite involving a number of C-H-forming/breaking steps, the assembly is chemoselective and the final products, 5-(2-furyl)-3(2H)-furanones, are formed in 59–96% yields. 相似文献
52.
Nina I. Giricheva Sergey N. Ivanov Anastasiya V. Ignatova Mikhail S. Fedorov Georgiy V. Girichev 《Molecules (Basel, Switzerland)》2020,25(24)
Structural factors have been identified that determine the gas-phase acidity of ortho-substituted benzenesulfonic acid, 2-XC6H4–SO3H, (X = –SO3H, –COOH, –NO2, –SO2F, –C≡N, –NH2, –CH3, –OCH3, –N(CH3)2, –OH). The DFT/B3LYP/cc-pVTZ method was used to perform conformational analysis and study the structural features of the molecular and deprotonated forms of these compounds. It has been shown that many of the conformers may contain anintramolecular hydrogen bond (IHB) between the sulfonic group and the substituent, and the sulfonic group can be an IHB donor or an acceptor. The Gibbs energies of gas-phase deprotonation ΔrG0298 (kJ mol–1) were calculated for all compounds. It has been set that in ortho-substituted benzenesulfonic acids, the formation of various types of IHB is possible, having a significant effect on the ΔrG0298 values of gas-phase deprotonation. If the –SO3H group is the IHB donor, then an ion without an IHB is formed upon deprotonation, and the deprotonation energy increases. If this group is an IHB acceptor, then a significant decrease in ΔrG0298 of gas-phase deprotonation is observed due to an increase in IHB strength and the A− anion additional stabilization. A proton donor ability comparative characteristic of the –SO3H group in the studied ortho-substituted benzenesulfonic acids is given, and the ΔrG0298 energies are compared with the corresponding values of ortho-substituted benzoic acids. 相似文献
53.
Ivan N. Bardasov Anastasiya U. Alekseeva Viktor A. Tafeenko Oleg V. Ershov 《合成通讯》2013,43(23):3343-3351
The one-pot reaction of aromatic aldehydes, malononitrile dimer, and triethylamine unexpectedly led to ammonium salts of not previously assumed 5,7-diamino-4-aryl-2-(dicyanomethyl)-1,4-dihydro-1,8-naphthyridine-3,6-dicarbonitriles, but the isomeric 5,7-diamino-4-aryl-2-(dicyanomethyl)-1,4-dihydro-1,6-naphthyridine-3,8-dicarbonitriles. Following neutralization and dehydrogenation led to the new, annulated with pyridine ring tricyanopyridines (TCPy). 相似文献
54.
Alexander A. Kamnev Yulia A. Dyatlova Odissey A. Kenzhegulov Anastasiya A. Vladimirova Polina V. Mamchenkova Anna V. Tugarova 《Molecules (Basel, Switzerland)》2021,26(4)
To demonstrate the importance of sample preparation used in Fourier transform infrared (FTIR) spectroscopy of microbiological materials, bacterial biomass samples with and without grinding and after different drying periods (1.5–23 h at 45 °C), as well as biogenic selenium nanoparticles (SeNPs; without washing and after one to three washing steps) were comparatively studied by transmission FTIR spectroscopy. For preparing bacterial biomass samples, Azospirillum brasilense Sp7 and A. baldaniorum Sp245 (earlier known as A. brasilense Sp245) were used. The SeNPs were obtained using A. brasilense Sp7 incubated with selenite. Grinding of the biomass samples was shown to result in slight downshifting of the bands related to cellular poly-3-hydroxybutyrate (PHB) present in the samples in small amounts (under ~10%), reflecting its partial crystallisation. Drying for 23 h was shown to give more reproducible FTIR spectra of bacterial samples. SeNPs were shown to contain capping layers of proteins, polysaccharides and lipids. The as-prepared SeNPs contained significant amounts of carboxylated components in their bioorganic capping, which appeared to be weakly bound and were largely removed after washing. Spectroscopic characteristics and changes induced by various sample preparation steps are discussed with regard to optimising sample treatment procedures for FTIR spectroscopic analyses of microbiological specimens. 相似文献
55.
Andrey V. Blinov Shahida A. Siddiqui Andrey A. Nagdalian Anastasiya A. Blinova Alexey A. Gvozdenko Vladislav V. Raffa Natalya P. Oboturova Alexey B. Golik David G. Maglakelidze Salam A. Ibrahim 《Arabian Journal of Chemistry》2021,14(7):103229
To solve the problem of insufficient intake of essential macro - and micronutrients into the human body, particularly in the case of the essential trace element Zinc, the possibility of enriching a socially significant product (milk) with various forms of Zinc is considered. The influence of Zinc-containing compounds on the colloidal milk system's dispersed composition and stability, photon correlation spectroscopy methods, acoustic and electroacoustic spectroscopy was established in this research. It has been shown that Zinc lysinatoriboflavinate, is a colloidal and chelated organic form of the essential trace element Zinc, having the most negligible effects on the composition and stability of the dispersed phase particles. This increases the average hydrodynamic radius of the dispersed phase by 5% and the ζ-potential by 10%.A quantum-chemical simulation of the interaction of milk κ-casein sites with various forms of the essential trace element Zinc in the QChem program was performed using the IQmol molecular editor. The mechanism of action of various forms of Zinc on the components of the dispersed system of milk, in particular milk protein (casein), is suggested. 相似文献
56.
The choice of appropriate density functional for the calculation of static first hyperpolarizability of azochromophores and stacking dimers
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Olga D. Fominykh Anastasiya V. Sharipova Marina Yu. Balakina 《International journal of quantum chemistry》2016,116(2):103-112
The effect of the stacked azo‐chromophore dimer formation on the values of static first hyperpolarizability is studied in the framework of the DFT‐based approach; calculations were also performed at the MP2 level. A number of dispersion‐corrected density functionals—В97D, ωВ97X‐D, and M06‐2X—is tested to calculate the structure of the dimer, the value of binding energy, and molecular nonlinear optical characteristics. According to the QTAIM analysis, the presence of bond critical points is revealed in the intermolecular region, the signs and values of topological characteristics giving evidence for the noncovalent van der Waals interaction between the chromophores. The formation of stacks results in moderate increase of dimer static first hyperpolarizability as compared to that of a single chromophore, the effect depending on the relative shift of the chromophores in dimer. In a special case of greatly shifted chromophores, this enhancement of the first hyperpolarizability becomes appreciable and achieves 72%. © 2015 Wiley Periodicals, Inc. 相似文献
57.
Trofimov BA Andriyankova LV Belyaeva KV Mal'kina AG Nikitina LP Afonin AV Ushakov IA 《The Journal of organic chemistry》2008,73(22):9155-9157
First examples of direct vinylation of 1-substituted imidazoles at the 2-position of the imidazole nucleus are described. 1-Substituted imidazoles 1a-e are C(2)-vinylated with 3-phenyl-2-propynenitrile (2) at room temperature without catalyst and solvent to afford 3-(1-organyl-1H-imidazol-2-yl)-3-phenyl-2-propenenitriles 3a-e, mainly (c.a. 95%) as (Z)-isomers, in 56-88% yield. The reaction is likely to involve the zwitterionic intermediates, which prototropically isomerizes to imidazole carbene and eventually undergoes the selective 3,2-shift of the functionalized vinyl substituent. 相似文献
58.
Anastasiya N. Khrustaleva Konstantin A. Frolov Victor V. Dotsenko Nicolai A. Aksenov Inna V. Aksenova Sergey G. Krivokolysko 《Tetrahedron letters》2017,58(50):4663-4666
The aminomethylation of 4,4-dialkyl-2,6-dioxopiperidine-3,5-dicarbonitriles (Guareschi imides) was studied for the first time. When the Guareschi imides were treated with primary aliphatic amines and an excess of formaldehyde, 2,4-dioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitriles were obtained in varying yields (15–67%). The structure of 9,9-dimethyl-7-(2-methylpropyl)-2,4-dioxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarbonitrile was studied by X-ray diffraction analysis. 相似文献
59.
Boris A. Trofimov Nina K. Gusarova Alexander V. Artem'ev Svetlana F. Malysheva Nataliya A. Belogorlova Anastasiya O. Korocheva 《Heteroatom Chemistry》2012,23(4):411-414
The straightforward reaction of 2‐bromopyridine with a PH3/H2 system (generated from phosphorus red and aqueous alkali) in the superbasic KOH/DMSO/(H2O) suspension under mild conditions (70°C, 1.5 h, atmospheric pressure) affords selectively and cleanly tris(2‐pyridyl)phosphine in 50% yield; no admixtures of the expected primary and secondary pyridylphosphines were observed in the crude product. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:411–414, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21030 相似文献
60.
Khakina EA Yurkova AA Peregudov AS Troyanov SI Trush VV Vovk AI Mumyatov AV Martynenko VM Balzarini J Troshin PA 《Chemical communications (Cambridge, England)》2012,48(57):7158-7160
Chlorofullerene C(60)Cl(6) undergoes highly selective reactions with thiols forming compounds C(60)[SR](5)H with high yields. These reactions open up straightforward synthetic routes to many functionalized fullerene derivatives, e.g. water-soluble compounds showing interesting biological activities. 相似文献