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Alexey V. Dobrydnev Bohdan V. Vashchenko Yulian M. Volovenko 《Tetrahedron letters》2018,59(16):1581-1582
We report the short and the simplest strategy for the synthesis of methyl 4-amino-2,2-dioxo-2,5-dihydro-1,2λ6-oxathiole-3-carboxylates bearing aliphatic substituents at the 5th position. A number of cyanohydrins were forced to react with methyl 2-(chlorosulfonyl)acetate to give the interim methyl 2-[(cyanomethoxy)sulfonyl]acetates that upon Et3N-mediated conditions underwent the CSIC [Carbanion mediated Sulfonate (Sulfonamido) Intramolecular Cyclization] reaction yielding the 5,5-disubstituted and spiranic methyl 4-amino-2,2-dioxo-2,5-dihydro-1,2λ6-oxathiole-3-carboxylates. 相似文献
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Oleksandr P. Demchuk Bohdan V. Bobovskyi Bohdan V. Vashchenko Dr. Oleksandr V. Hryshchuk Artem Skreminskyi Dr. Anton V. Chernykh Dr. Viktoriia S. Moskvina Dr. Olga V. Hordiyenko Prof. Dr. Dmitriy M. Volochnyuk Prof. Dr. Oleksandr O. Grygorenko 《European journal of organic chemistry》2023,26(24):e202300292
Synthesis and physicochemical characterization of all possible cis- and trans-1,3-disubstituted cyclobutane-derived amines and carboxylic acids bearing mono-, di- and trifluoromethyl groups at the C-3 position is disclosed. Tetramethylammonium fluoride (TMAF)- or morpholinosulfur trifluoride (Morph-DAST)-mediated nucleophilic fluorination of appropriate cis- and trans-diastereomeric substrates was used as the key step for the preparation of CH2F- and CHF2-substituted derivatives. To obtain the corresponding cis- and trans-isomeric CF3-substituted derivatives, resolution of known 3-(trifluoromethyl)cyclobutanecarboxylic acid (obtained as a mixture of diastereomers) was applied. The proposed procedures were suitable for the preparation of corresponding fluoroalkyl-substituted cyclobutane-derived amines and carboxylic acids on up to 50 g scale. All 12 building blocks obtained were characterized by measuring dissociation constants (pKa) and lipophilicities (LogP, for model derivatives) to evaluate the effect of the fluoroalkyl substituents on their physicochemical properties relevant to further drug discovery applications. 相似文献
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Maria Poienar Vincent Hardy Bohdan Kundys Kiran Singh Antoine Maignan Françoise Damay Christine Martin 《Journal of solid state chemistry》2012
Platelet-like single-crystals of delafossite CuCrO2 have been successfully grown and characterised by X-ray diffraction and pole figures, scanning electron and atomic force microscopy. Transport measurements reveal that the resistivity is highly anisotropic, with a ratio of about 35 at 300 K between the in- and out-of-plane directions, reflecting the layered crystal structure. The magnetization and specific heat data show that CuCrO2 undergoes a unique antiferromagnetic transition at TN=24.0 K, in contrast to a recent report on CuCrO2 single-crystals [16] showing the existence of two magnetic transitions, TN1=24.2 K and TN2=23.6 K, depending on the orientation of the applied magnetic field along and perpendicular to c, respectively. 相似文献
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The single crystals of triglycine sulfate doped with bivalent and tetravalent Pt‐ions and with L‐alanine (LADTGS/Pt(II) and LATGS/Pt(IV)) were grown in the ferroelectric phase from low temperature solutions. Using stick seeds the full‐shaped crystals with many growth pyramids have been prepared. The growth rate along the axis c of the doped crystals is much higher than in an undoped one. Morphology, domain structure and P‐E hysteresis loops have been investigated. The effect of the dopant on the growth velocity is explained on the basis of catalytic action of supposed platinum complexes. The first series of the pyroelectric detectors have been prepared from these materials and their fundamental parameters are presented. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Edmund F. Jordan Bohdan Artymyshyn Anthony Speca A. N. Wrigley 《Journal of polymer science. Part A, Polymer chemistry》1971,9(11):3349-3365
The heats of fusion and the melting transitions of the crystallinity present in the side chains were determined for selected copolymers incorporating n-octadecyl acrylate or vinyl stearate. A major purpose of this investigation was to ascertain the effect of interrupting the long ordered 18-carbon side chains by randomly interspersed amorphous side chains of various lengths. For this purpose the lower acrylate homologs (C1 through C8 and including oleyl, C8) were copolymerized over the composition range with n-octadecyl acrylate. It was found that simple dilution of the crystalline component (from comonomer b) by the amorphous component (from comonomer a) governed the decline in the heats of fusion and the fraction of crystallinity present. High crystallization rates were encountered because equilibrium crystallinity was nearly achieved for most of the copolymers. Melting point depression was less than theory in copolymers having short amorphous comonomer side chain lengths, but approached the theoretical depression as these side chains became very long. Thus the outer methylene sequences (the crystalline sequences) of the fatty co-units could bridge the smaller amorphous a units, giving rise to larger crystal sizes than theory specified. Main-chain stiffness, when present in the melt, had a small effect on the distribution of crystallite sizes but exhibited a much larger influence in preventing the attainment of equilibrium crystallinity, especially at high amorphous comonomer compositions. However, crystallinity was still high compared with that of copolymers described in the literature crystallizing through their main-chain units. When long blocks of crystalline segments were present (as in compositionally heterogeneous vinyl stearate copolymers), melting point depression was small and followed the theoretical probability sequence function. 相似文献