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31.
A series of novel optically active 1,3‐aminoalcohols based on cis‐(1R,2S)‐2‐benzamidocyclohexanecarboxylic acid and trans‐(1R,2R)‐2‐benzamidocyclohexanecarboxylic acid were synthesized and used in the asymmetric diethylzinc addition to aromatic aldehydes. Not only the enantioselectivity but also the stereochemistry of the product were controlled by the N‐substituents and the substituents on the vicinity carbon to hydroxyl group of the cis‐derivatives. 相似文献
32.
33.
Yoshinori Kamiya Yasutoshi Naito Takuji Hirose Keishin Mizoguchi 《Journal of Polymer Science.Polymer Physics》1990,28(8):1297-1308
Sorption of N2, O2, Ar, CH4, CO2, C2H4, and C2H6 in poly (dimethyl siloxane) liquid and rubber and the dilation of the polymers due to sorption of the gases are studied at 25°C under pressures up to 50 atm. In the liquid, the sorption isotherms for low-solubility and high-solubility gases are described by Henry's law and the Flory–Huggins equation, respectively. Gas sorption in the rubber, which contains a 29 wt % silica filler, follows the dual-mode sorption model, though marked hysteresis is observed in the sorption of O2 and CH4. The dilation isotherms increase linearly or exponentially in both polymers with increasing pressure. Considering that gas molecules adsorbed into micropores of the filler particles do not participate in the dilation, partial molar volumes of the dissolved gases in the rubber are determined from data of sorption and dilation. The values are nearly equal to the partial molar volumes in the liquid (48–60 cm3/mol). 相似文献
34.
Hiroki Hirai Kiichi Nakajima Soichiro Nakatsuka Kazushi Shiren Jingping Ni Shintaro Nomura Toshiaki Ikuta Takuji Hatakeyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(46):13785-13789
The development of a one‐step borylation of 1,3‐diaryloxybenzenes, yielding novel boron‐containing polycyclic aromatic compounds, is reported. The resulting boron‐containing compounds possess high singlet‐triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light‐emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one‐step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron‐fused benzo[6]helicene. 相似文献
35.
Takuji MamemuraNaonobu Tanaka Azusa ShibazakiTohru Gonoi Jun’ichi Kobayashi 《Tetrahedron letters》2011,52(28):3575-3578
Two new meroterpenoids, yojironins A (1) and B (2), were isolated from the whole plants of Hypericum yojiroanum, together with two new prenylated acylphloroglucinols, yojironins C (3) and D (4). Their structures were elucidated by spectroscopic data. Yojironins A (1) and B (2) are biogenetically unique meroterpenoids, which seem to be composed of two acetate units with a 2-methylbutanoyl group and three isoprene units. Yojironin A (1) exhibited antimicrobial activity. 相似文献
36.
Kodama K Sekine E Hirose T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(41):11527-11534
Ternary organic crystals consisting of an L-tartaric acid-derived dicarboxylic acid, a commercially available achiral diamine, and a chiral secondary alcohol have been developed and characterized by X-ray crystallography. 1D, 2D, and 3D hydrogen-bonded supramolecular networks were constructed, depending on the structure of the diamine used. Benzylic and aliphatic secondary alcohols were enantioselectively incorporated into the crystal and were successfully enantioseparated with up to 86 and 79% enantiomeric excess (ee), respectively. Selective incorporation of one enantiomer of 2-butanol, which is a small chiral aliphatic alcohol, was achieved by the cooperative effects of hydrogen bonds, CH···π interactions, and van der Waals interactions between the guest and host molecules, with the aid of two water molecules. The high host potential of the binary supramolecular system is mainly attributed to the skewed conformation of two rigid aromatic groups of tartaric acid derivatives, which prevents dense packing of the molecules and enhances the formation of multicomponent inclusion crystals. 相似文献
37.
A rhodium-catalyzed asymmetric addition of readily available potassium organotrifluoroborates to both N-tosyl and N-nosyl ketimines has been developed. High enantioselectivity has been achieved by using a chiral diene ligand, and the nosyl group of the addition products can be easily removed while retaining the enantiomeric purity. 相似文献
38.
A rhodium-catalyzed 1,4-addition of sodium tetraarylborates to β,β-disubstituted α,β-unsaturated esters has been developed. Highly efficient asymmetric catalysis has also been described to create quaternary carbon stereocenters at the β-position of esters by tuning the ester group of substrates and employing a readily available chiral diene ligand. 相似文献
39.
Shintani R Narui R Tsutsumi Y Hayashi S Hayashi T 《Chemical communications (Cambridge, England)》2011,47(21):6123-6125
Novel chiral phosphorus-olefin bidentate ligands have been synthesized in a few steps from a readily available enantiopure compound. These ligands have been applied to a rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl aldimines, achieving high yield and enantioselectivity. 相似文献
40.
Unexpected vibrations on a cylindrical filter made of nonwoven fabrics were clarified experimentally. Two types of filter with length L=1.8 m and 3.7 m, both 45 cm in diameter and 1.08 mm in thickness, were used. This is a new type of aeroelastic vibration phenomenon because the filter is a closed cylindrical vessel. In addition, the flow velocity of inner air was very slow and inner air flowed out slowly from the filter surface. The velocity distribution of air flow from a fan duct as well as the frequency and amplitude of the filter vibration were measured for two types of filter. By setting up a roll core panel at the outlet of the fan duct, we could rectify the outflow and suppressed the vibration of the shorter filter with L=1.8 m. However, this method was not adequate for the longer filter with L=3.7 m, and we could suppress the vibration by shielding the inner surface of the filter at the top region. 相似文献