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31.
Kurita T Aoki F Mizumoto T Maejima T Esaki H Maegawa T Monguchi Y Sajiki H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(11):3371-3379
The Pd/C-catalyzed H(2)-D(2) exchange reaction using a H(2)-D(2)O combination provided a general, efficient and environmentally friendly route for the preparation of deuterium gas (D(2)). H(2) sealed in a reaction flask was converted into nearly pure D(2), which could be used for the Pd/C-catalyzed one-pot reductive deuteration of various reducible functionalities and the chemoselective one-pot deuterogenation of olefin and acetylene. Additionally, we established the capturing method of the generated D(2) in a balloon, which was successfully applied to the Pd/C-catalyzed reductive mono-N-alkylation of a primary amine using nitrile as the alkylating reagent. 相似文献
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Dr. Takayuki Iwata Ryusei Kawano Takuto Fukami Prof. Dr. Mitsuru Shindo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(12):e202104160
The triptycene scaffold has been ring-opened by using a retro-Friedel-Crafts-type reaction under acidic conditions to give its corresponding anthrone product. 9-Hydroxytriptycenes and unsubstituted triptycene undergo ring-opening reaction under strongly acidic conditions, such as with TfOH. An investigation of the substitution effect has revealed that the electron-donating group on the arene moiety allows the reaction to proceed in the presence of a weaker acid, such as TFA. In addition, the reaction has been successfully applied toward the synthesis of tetracene. 相似文献
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Takuto Ohsato Dr. Yuri Okuno Prof. Dr. Shintaro Ishida Prof. Dr. Takeaki Iwamoto Dr. Ka‐Ho Lee Prof. Dr. Zhenyang Lin Prof. Dr. Makoto Yamashita Prof. Dr. Kyoko Nozaki 《Angewandte Chemie (International ed. in English)》2016,55(38):11426-11430
A potassium diboryllithate (B2LiK) was synthesized and structurally characterized. DFT calculations, including NPA and AIM analyses of B2LiK, revealed ionic interactions between the two bridging boryl anions and Li+ and K+. Upon standing in benzene, B2LiK deprotonated the solvent to form a hydroborane and a phenylborane. On the basis of DFT calculations, a detailed reaction mechanism, involving deprotonation and hydride/phenyl exchange processes, is proposed. An NBO analysis of the transition state for the deprotonation of benzene suggests that the deprotonation should be induced by the coordination of benzene to the K+. 相似文献
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Kurita T Hattori K Seki S Mizumoto T Aoki F Yamada Y Ikawa K Maegawa T Monguchi Y Sajiki H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(2):664-673
The Pd/C-catalyzed efficient and regioselective hydrogen-deuterium (H-D) exchange reaction on the benzylic site proceeded in D2O in the presence of a small amount of H2 gas. The use of the Pd/C-ethylenediamine complex [Pd/C(en)] as a catalyst instead of Pd/C led to the efficient deuterium incorporation into the benzylic site of O-benzyl protective groups without hydrogenolysis. These H-D exchange reactions provide a post synthetic and D(2)-gas-free deuterium-labeling method on a wide variety of benzylic sites using D2O as the deuterium source and heterogeneous Pd/C or Pd/C(en) as a reusable heterogeneous palladium catalyst under mild and neutral conditions. 相似文献
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Rungthip Kunthom Takuto Adachi Yujia Liu Nobuhiro Takeda Masafumi Unno Ryoji Tanaka 《化学:亚洲杂志》2019,14(23):4179-4182
Novel polyhedral structures were prepared with a butterfly‐shape composed of oligosiloxane wings and a double‐decker silsesquioxane (DDSQ) body. The compounds were synthesized in two steps from commercially available alkoxysilanes, and their structures were confirmed using spectroscopic methods and X‐ray crystallography. Not like other phenyl‐substituted cage silsesquioxanes, these butterfly cages show very good solubility in common organic solvents. The crystal structures clearly showed their unique features: a larger space with longer siloxane chains and a very flexible framework. Moreover, these compounds are thermally stable with a Td5 (5 % weight loss temperature) over 320 °C. 相似文献
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Takafumi Saito Kenshu Fujiwara Yusuke Sano Takuto Sato Yoshihiko Kondo Uichi Akiba Yusuke Ishigaki Ryo Katoono Takanori Suzuki 《Tetrahedron letters》2018,59(14):1372-1376
In our previously reported method for the construction of the IJKLM-ring of ciguatoxin 3C (CTX3C), the lengthy synthetic process for the intermediate C42–C52 (L-ring) segment was problematic. Therefore, a new and improved procedure for the C42–C52 segment, having modified protecting groups, was developed. The new route includes a chirality transferring Ireland-Claisen rearrangement for the construction of the vicinal dimethyl branching at C47–48, a one-pot cyclization process for the establishment of the stereocenters at C45 and C46 as well as the γ-hydroxy δ-lactone framework corresponding to the L-ring, and Brown’s asymmetric crotylboration for the installation of the stereocenters at C43 and C44. The new C42–C52 segment was successfully coupled with the previously reported C32–C41 (I-ring) segment to produce the IJKLM-ring. 相似文献
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Quantum chemical explorations of potential energy surfaces showed that acetylene produces various products starting from molecular arrays in short distances of 1.3–2.5 Å. Arrays of (C2H2)2 gave cyclobutadiene, tetrahedrane, and acetylene dimers. Arrays of (C2H2)3 gave benzene, prismane, benzvalene, Dewar benzene, and acetylene trimers. Arrays of (C2H2)4 gave cubane, cyclooctatetranene, and acetylene tetramers. Different forms of initial arrays yielded different sets of products; a parallel array of two monomers gave cyclobutadiene, whereas a cross array gave tetrahedrane. Initial molecular arrays with unusually close contacts were estimated to require local forces of 1–9 × 10−8 N. © 2019 Wiley Periodicals, Inc. 相似文献