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991.
Kobayashi T Hasegawa F Hirose Y Tanaka K Mori H Katsumura S 《The Journal of organic chemistry》2012,77(4):1812-1832
The asymmetric one-pot 6π-azaelectrocyclization of alkenyl vinyl stannane, ethyl (Z)-2-iodo-4-oxobutenoate, and (-)-7-isopropyl-cis-aminoindanol in the presence of a Pd(0) catalyst stereoselectively produced the tetracyclic aminoacetal compounds, resulting from the four-bond formation accompanying by controlling the stereochemistry at the two asymmetric centers. The produced cyclic aminoacetals can be regarded as synthetic precursors of substituted chiral piperidines, and the syntheses of 2,4- and 2,4,6-substituted piperidines were realized from the obtained aminoacetals by the stereoselective hydrogenation of the double bond conjugated with the C-4 ester group and alkylation at the aminoacetal moiety. In addition, the stereoselective synthesis of an indolizidine alkaloid, (-)-dendroprimine, and its three stereoisomers, (+)-7-epidendroprimine, (+)-5-epidendroprimine, and (+)-5,7-epidendroprimine, were achieved. 相似文献
992.
Wang WH Hull JF Muckerman JT Fujita E Hirose T Himeda Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9397-9404
Deuterated compounds have received increasing attention in both academia and industrial fields. However, preparations of these compounds are limited for both economic and practical reasons. Herein, convenient generation of deuterium gas (D(2)) and the preparation of deuterated compounds on a laboratory scale are demonstrated by using a half-sandwich iridium complex with 4,4'-dihydroxy-2,2'-bipyridine. The "umpolung" (i.e., reversal of polarity) of a hydrogen atom of water was achieved in consecutive reactions, that is, a cationic H(+)/D(+) exchange reaction and anionic hydride or deuteride transfer, under mild conditions. Selective D(2) evolution (purity up to 89?%) was achieved by using HCO(2)H as an electron source and D(2)O as a deuterium source; a rhodium analogue provided HD gas (98?%) under similar conditions. Furthermore, pressurized D(2) (98?%) without CO gas was generated by using DCO(2)D in D(2)O in a glass autoclave. Transfer deuterogenation of ketones gave α-deuterated alcohols with almost quantitative yields and high deuterium content by using HCO(2)H in D(2)O. Mechanistic studies show that the H(+)/D(+) exchange reaction in the iridium hydride complex was much faster than β-elimination and hydride (deuteride) transfer. 相似文献
993.
The search of nuclear bound states of ${\bar{K}}$ in few-body nuclear systems such as K ? pp, can be extended from the nuclear medium to the vacuum, using the glue-rich ${\Upsilon(1S)}$ decays at B-factories. Here the possibility for such a measurement at the future SuperB factory is discussed. 相似文献
994.
995.
A high-pressure apparatus with cubic-anvil device has been successfully working for more than 10 years at low temperatures down to 2?K under quasi-hydrostatic pressure up to 10?GPa in study of solid-state physics. Main parts of it are composed of a set of compact cubic-anvils, a top-loading high-pressure cryostat and a 250?ton press. All the particulars of the cubic-anvil apparatus are given, including pressure calibrations at low temperature. 相似文献
996.
Noritaka Kuroda Yasuo Oeda Giyw Kido Masayasu Takeda Yuichiro Nishina Yasuaki Nakagawa 《高压研究》2013,33(1):65-66
Abstract The magneto-optical spectra of the R1 and R2 lines of Cr3+ ions in alexandrite have been measured under hydrostatic pressures and magnetic fields up to 6 GPa and 15 T, respectively. The spins of the excited states, 2E, have the Heisenberg-type characters at atmospheric pressure, though the g-values are anisotropic with the values between 1.3 and 2.0. The g-values for the direction parallel to the α-axis remain unchanged with increasing pressure, while for the directions normal to the α-axis they are reduced appreciably. The fine structure parameters of spins in the ground state, 4A2, exhibit quite a similar behavior. The R1-R2 splitting is reduced also by pressure. These properties are the evidences that the spins of the 2E states become of the king-type under pressures above about 15 GPa. The mechanism of such the change of spin character is discussed quantitatively on the basis of a crystal field model. 相似文献
997.
Abstract The lattice constants of Hf1-xTaxFe2 with C14 structure were measured at room temperature under pressure up to 5 GPa. The magnetic phase diagram obtained as a function of pressure was compared with that obtained as a function of Ta concentration x. It is shown that changes in lattice constants by applying pressure and /or by substituting Ta for Hf affect remarkably the magnetic phase stability, which is consistent qualitatively with a recent theoretical prediction based on the local spin density approximation. 相似文献
998.
Yoshihisa Mori Yuichi Akahama Mototada Kobayashi Haruki Kawamura Utako Endo Tomoji Kawai 《高压研究》2013,33(1-6):411-413
Abstract A new high pressure x-ray diffraction system has been developed, which consists of a diamond anvil cell, an imaging plate as a detector and an 18 kW rotating anode type generator. By this system we found an anisotropic compression and anomalies in linear compressibility for the Bi-oxide superconductors. 相似文献
999.
1000.