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81.
Copper Causes Regiospecific Formation of C4F8‐Containing Six‐Membered Rings and their Defluorination/Aromatization to C4F4‐Containing Rings in Triphenylene/1,4‐C4F8I2 Reactions
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Kerry C. Rippy Dr. Eric V. Bukovsky Dr. Tyler T. Clikeman Dr. Yu‐Sheng Chen Dr. Gao‐Lei Hou Dr. Xue‐Bin Wang Dr. Alexey A. Popov Dr. Olga V. Boltalina Prof. Steven H. Strauss 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):874-877
The presence of Cu in reactions of triphenylene (TRPH) and 1,4‐C4F8I2 at 360 °C led to regiospecific substitution of TRPH ortho C(β) atoms to form C4F8‐containing rings, completely suppressing substitution on C(α) atoms. In addition, Cu caused selective reductive‐defluorination/aromatization (RD/A) to form C4F4‐containing aromatic rings. Without Cu, the reactions of TRPH and 1,4‐C4F8I2 were not regiospecific and no RD/A was observed. These results, supported by DFT calculations, are the first examples of Cu‐promoted 1) regiospecific perfluoroannulation, 2) preparative C?F activation, and 3) RD/A. HPLC‐purified products were characterized by X‐ray diffraction, low‐temperature PES, and 1H/19F NMR. 相似文献
82.
83.
Il'yas S. Nizamov Alexey E. Popovich Elvira S. Batyeva Nail M. Azancheev Vladimir A. Al'fonsov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):167-178
Abstract The reactions of tetraphosphorus decasulfide and Lawesson's reagent with tetra-, tri- and dialkoxysilanes were studied. On the basis of these reactions, new S-silyl esters of phosphorus(V) thioacids have been prepared. The prepared compounds were identified by IR, 1H, and 31P NMR and mass spectra as well as elemental analyses. 相似文献
84.
Chuiko Alexey Philonenko Ludmila Borisevich Anatoly Lozinsky Miron 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Heterocyclic derivatives of gem-bisphosphonates exhibit various biological activities. We have found that thiazolium substituted bisphosphonic acids can be obtained by two-step synthesis from amino-bisphosphonates (I). Reaction of (I) with isothiocyanates in alkohol in the presence of triethylamine led to corresponding thioureas (II) obtained as natrium or triethylamonium salts [1]. Further treatment of (II) with α-bromoketones give aminothiazoles (III) with a good yield. As a rule only less hindered nitrogen atom is involved into the cyclization with formation of one from two of possible isomers. 相似文献
85.
86.
Dr. Claudia Kolbeck Dr. Alexey Deyko Dr. Takashi Matsuda Florian T. U. Kohler Prof. Dr. Peter Wasserscheid Dr. Florian Maier Prof. Dr. Hans-Peter Steinrück 《Chemphyschem》2013,14(16):3726-3730
We present the first systematic study of the influence of temperature on the degree of surface enrichment of 1-alkyl-3-methylimidazolium-based ionic liquids (ILs). Using angle-resolved X-ray photoelectron spectroscopy, we demonstrate that the degree of surface enrichment strongly decreases with increasing temperature for all the studied ILs. For ILs with the same cation, but different anions, [C8C1Im]Br, [C8C1Im][TfO] and [C8C1Im][Tf2N], no significant differences of the temperature-induced partial loss of surface enrichment are found. Measurements for [C4C1Im][TfO], [C8C1Im][TfO] and [C18C1Im][TfO] indicate a small effect of the chain length. For [C18C1Im][TfO], a continuous decrease of alkyl surface enrichment is found with increasing temperature, with no abrupt changes at the phase-transition temperature from the smectic A to the isotropic phase, indicating that the surface enrichment is not affected by this phase transition. 相似文献
87.
Alexey Bobrovsky Valery Shibaev Věra Hamplová Miroslav Kašpar Vladimira Novotna Milada Glogarová 《Liquid crystals》2013,40(9):989-997
A photoinduced phase transition and helix untwisting in a new liquid crystal forming the SmC* phase were studied in detail. The compound consists of a cinnamoyl photosensitive fragment with C?=?C double bond capable of photoisomerisation and photocycloaddition. It was shown that ultraviolet (UV) irradiation (365 nm) induces an extreme decrease in phase transitions temperatures (SmC*–SmA*, SmA*–N*, N*–I). Vertically aligned samples in the SmC* phase cause selective light reflection in the visible spectral range. The light action results in a noticeable helix untwisting that causes a shift in the selective light reflection peak to the long-wavelength spectral region. The temperature dependence of spontaneous polarisation P s was measured and it was found that UV irradiation induces a decrease in the values of P s. Photo-optical phenomena taking place in the liquid crystal are attributed to the formation of photoproducts having low anisometry, which disrupts mesophases. 相似文献
88.
Tyler T. Clikeman Dr. Igor V. Kuvychko Dr. Natalia B. Shustova Dr. Yu‐Sheng Chen Dr. Alexey A. Popov Dr. Olga V. Boltalina Prof. Steven H. Strauss 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5070-5080
The sequential addition of CN? or CH3? and electrophiles to three perfluoroalkylfullerenes (PFAFs), Cs‐C70(CF3)8, C1‐C70(CF3)10, and Cs‐p‐C60(CF3)2, was carried out to determine the most reactive individual fullerene C atoms (as opposed to the most reactive C?C bonds, which has previously been studied). Each PFAF reacted with CH3? or CN? to generate metastable PFAF(CN)? or PFAF(CH3)22? species with high regioselectivity (i.e., one or two predominant isomers). They were treated with electrophiles E+ to generate PFAF(CN)(E) or PFAF(CH3)2(E)2 derivatives, also with high regioselectivity (E+=CN+, CH3+, or H+). All of the predominant products, characterized by mass spectrometry and 19F NMR spectroscopy, are new compounds. Some could be purified by HPLC to give single isomers. Two of them, C70(CF3)8(CN)2 and C70(CF3)10(CH3)2(CN)2, were characterized by single‐crystal X‐ray diffraction. DFT calculations were used to propose whether a particular reaction is under kinetic or thermodynamic control. 相似文献
89.
Natalia A. Romanova Maria A. Fritz Dr. Kaichin Chang Dr. Nadezhda B. Tamm Dr. Alexey A. Goryunkov Prof. Lev N. Sidorov Dr. Chuanbao Chen Prof. Shangfeng Yang Prof. Erhard Kemnitz Prof. Sergey I. Troyanov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(35):11707-11716
Trifluoromethylation of a higher fullerene mixture with CF3I was performed in ampoules at 550 °C. HPLC separation followed by crystal growth and X‐ray diffraction study resulted in the structure elucidation of nine CF3 derivatives of D2d‐C84 (isomer 23). The molecular structures of C84(23)(CF3)4, C84(23)(CF3)8, C84(23)(CF3)10, C84(23)(CF3)12, two isomers of C84(23)(CF3)14, two isomers of C84(23)(CF3)16, and C84(23)(CF3)18 were discussed in terms of their addition patterns and the relative formation energies. Extensive theoretical DFT calculations were performed to identify the most stable molecular structures. It was found that the addition of CF3 groups to the C84(23) fullerene is governed by two main rules: no additions in positions of triple hexagon junctions and predominantly para additions in C6(CF3)2 hexagons on the fullerene cage. The only exception with an isolated CF3 group in C84(23)(CF3)12 is discussed in more detail. 相似文献
90.
Dr. Michael Bodensteiner Prof. Dr. Alexey Y. Timoshkin Dr. Eugenia V. Peresypkina Dr. Ulf Vogel Prof. Dr. Manfred Scheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):957-963
The reaction of [{(CO)5W}PRH2] (R=H, Ph) with H3Al ? NR3 (R=Et, Me) leads to the formation of four‐membered heterocyclic compounds [({(CO)5W}P(H)AlH ? NEt3)2] and [({(CO)5W}PhPAlH ? NMe3)2]. Upon dissolving the solid compounds, fast equilibria between the isomers are observed on the NMR timescale. Further insight into the stability and reactivity of the isomers was gained by applying theoretical methods. DFT calculations predict that hydrogen elimination in the case of [({(CO)5W}PhPAlH ? NMe3)2] may be reversible. 相似文献