著者

Tsuneomi Kawasaki Hitomi Ozawa Masateru Ito Kenso Soai

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.40, no.3, pp.320-321, 2011-03-05 (Released:2011-02-19)

参考文献数

40

被引用文献数

38

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Enantioselective synthesis has been achieved using chiral compounds arising from mono- and dideuterated methyl groups as chiral inducers in conjunction with asymmetric autocatalysis. The absolute configuration of the product was controlled by the small degree of chirality generated by the difference between the partially deuterated methyl groups (CDH2 and CD2H) and the non-deuterated methyl group (CH3) in N-benzoyl-α-methylalanine.

著者

Eiko Mieda Takahiro Sasamori Shohei Sase Kei Goto Norihiro Tokitoh

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.40, no.2, pp.196-197, 2011-02-05 (Released:2011-01-22)

参考文献数

18

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We report here the attempted synthesis of a stable 1-fluoro-2-hydrosilene bearing a Bpq group, which is a bulky aryl group bearing a cavity-shaped framework. We have successfully synthesized an overcrowded benzyldifluorosilane as a precursor. Treatment of the benzyldifluorosilane with 2 equiv of t-BuOK in THF afforded the corresponding benzyl anion, the structure of which showed a unique feature as a fluorosilene–KF complex.

著者

Izumi Iwakura Atushi Yabushita Takayoshi Kobayashi

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.39, no.4, pp.374-375, 2010-04-05 (Released:2010-03-06)

参考文献数

34

被引用文献数

28

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The detailed processes in the Claisen rearrangement were observed. The process was vibrationally excited in the electronic ground state by a stimulated Raman process using a 5-fs pulse. The Claisen rearrangement was found to follow a three-step pathway. At first, the C4–O bond is weakened to generate a bis-allyl-like intermediate. Next, the formation of a weak C1–C6 bond results in the generation of an aromatic-like intermediate. Finally, C4–O breaking and C1–C6 formation occur simultaneously to generate the product.

著者

Isamu Shiina Keisuke Ono Kenya Nakata

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.40, no.2, pp.147-149, 2011-02-05 (Released:2011-01-08)

参考文献数

18

被引用文献数

48

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A variety of optically active 1-heteroarylalkanols and their esters, which include heteroaromatic moieties, such as 2-furyl, 2-thienyl, 3-thienyl, 2-thiazoyl, 2-benzothiazoyl, and 2-benzoxazoyl groups, are efficiently produced by a novel asymmetric esterification. The transition states that form the desired (R)-esters from the (R)-1-heteroarylalkanols are determined by DFT calculations, and the structural features of these transition states are systematically discussed.

著者

Daichi Kitagawa Seiya Kobatake

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.40, no.1, pp.93-95, 2011-01-05 (Released:2010-12-16)

参考文献数

37

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A photochromic diarylethene having methoxymethyl groups at the reactive carbons was synthesized, and the thermal stability of the closed-ring isomer was examined. The closed-ring isomer of the diarylethene caused both the thermal cycloreversion and a thermally irreversible reaction at 120 °C. The structure of the thermal product was determined by 1H NMR, MS, and X-ray crystallographic analysis.

著者

Hiroki Oguri

出版者

The Chemical Society of Japan

雑誌

Bulletin of the Chemical Society of Japan (ISSN:00092673)

巻号頁・発行日

vol.80, no.10, pp.1870-1883, 2007-10-15 (Released:2007-10-12)

参考文献数

98

被引用文献数

13

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Ciguatoxins are the major causative toxins in ciguatera seafood poisoning. The limited availability of ciguatoxins has precluded structural elucidation and development of a reliable and specific immunoassay for detecting the toxins in contaminated fish. To seek a solution for the longstanding problem of ciguatera, we addressed the synthetic challenge by utilizing rationally designed model compounds of ciguatoxins. The C2 configuration and entire absolute configuration of ciguatoxin were successfully elucidated with minutest amounts of natural toxins, using an approach which combined partial structure synthesis, microscale chemical transformations, and the CD exciton chirality method. On the basis of the absolute configuration, the partial structures of ciguatoxins were designed and synthesized as haptens for the preparation of anti-ciguatoxin antibodies. Monoclonal antibodies (mAbs) against both ends of ciguatoxin CTX3C were prepared by immunization of mice with protein conjugates of synthetic haptens of the ABCDE-ring and the IJKLM-ring, in place of the natural toxin. Haptenic groups with surface areas larger than 400 Å2 were required to produce mAbs, which could bind strongly to CTX3C itself. A direct sandwich enzyme-linked immunosorbent assay (ELISA) using these mAbs was shown to detect CTX3C at the ppb level with no cross-reactivity against other related marine toxins, including brevetoxin A, brevetoxin B, okadaic acid, or maitotoxin. In order to make the sandwich immunoassay protocol a general method for detecting other ciguatoxins congeners, the preparation of mAbs for the left-end of ciguatoxin was investigated. Expeditious synthesis of the left end of ciguatoxin with installation of the 3-butene-1,2-diol side-chain of the A-ring as well as surface plasmon resonance (SPR) analysis of the antibody–hapten interactions are also described.

著者

Hiroyasu Tamura Yoshihiro Shinohara Tatsuo Arai

出版者

The Chemical Society of Japan

雑誌

Chemistry Letters (ISSN:03667022)

巻号頁・発行日

vol.39, no.3, pp.240-241, 2010-03-05 (Released:2010-02-06)

参考文献数

22

被引用文献数

30

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Ionic liquids having a photoresponsive stilbene chromophore were prepared and their properties were examined. While the trans isomers were all solid, most of the cis isomers were liquid at room temperature. The trans isomers give fluorescence emission with a quantum yield of ca. 0.02, while the cis isomers practically give no fluorescence. Thus, we could photochemically switch the properties of ionic liquid as well as emission properties by photochemical processes.