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Epnselenonium Ion Intermediate : Isolation and Utilization in Carbon-Carbon Band Formations

Research Project

Project/Area Number 09650957
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Synthetic chemistry
Research InstitutionKYOTO UNIVERSITY

Principal Investigator

TOSHIMITSU Akio  Institute for Chemical Research, KYOTO UNIVERSITY Associate Professor, 化学研究所, 助教授 (60127107)

Project Period (FY) 1997 – 1998
Project Status Completed (Fiscal Year 1998)
Budget Amount *help
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1997: ¥2,500,000 (Direct Cost: ¥2,500,000)
KeywordsEpiselenonium Ion / Steric Protection / Election-withdrawing Group / Carbon-Carbon Poond Formation / Chiral Carbon / トリ-t-ブチルフェニル基
Research Abstract

This report is the summary of the preliminary results obtained by the research project. Three sections constitute this report and their abstracts are as follows.
The first part describes that, in the Ritter-type reactions starting from chiral alcohols to afford amides through the anchimeric assistance of the arylseleno group, the enantiomeric excesses of the amides are better when the bulky substituents are introduced into the aryl groups. We deduced that the racemization of the chiral episelenonium ion intermediates are suppressed by the steric protection of the selenium atom from the attack of the nucleophiles. In order to support this hypothesis, we carried out the reactions of the episelenonium ion intermediates with carbon nucleophiles and found that the formation of the carbon-selenium bonds are completely suppressed by the steric protection. Thus, the steric protection was clarified to be important to stabilize the episelenonium ion intermediates.
The second part describes that, in the Rider-type reactions described above, not only the bulky substituents but also the electron-withdrawing substituents contribute to suppress the racemization of the chiral episelenonium ion intermediates. It is also clarified that these two effects work additively. It is pointed out that the racemization of the chiral episelenonium ion intermediates proceeds through the hypervalent selenium compounds.
The results of the studies on the hypervalent selenium compounds are described in the third section. It is clarified that the formation of hypervalent selenium compounds is much more facile as compared to the sulfur compounds and the hypervalent selenium compounds can be utilized in the organic syntheses.

Report

(3 results)
  • 1998 Annual Research Report   Final Research Report Summary
  • 1997 Annual Research Report
  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] 年光昭夫: "Prevention of Racemization of the chiral Carbon in the Episelemonium Ion Intermechate : steric Protection and Electron-with drowing Effect" Phosphorus Sulphur and Silicon. 136, 137, 138. 649-652 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] 年光昭夫: "Organoselenium chemistry, A Practical Approach" Oxford University Press 印刷中, (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] A.Toshimitsu: "Prevention of Racemization of Chiral Carbon in the Epnselenouiam Ion Intermediate : steric Protection and Electron-withdrawing Effect" Phosphorus, Sulphur, and Silicon. 136,137,138. 649-652 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] A.Toshimitsu: "Reactions of Selenons" Organoselenium chemistry A Practical Approach. Oxford Press (in press). (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1998 Final Research Report Summary
  • [Publications] A.Toshimitsu,K-Nakano K.Tomoo: "Prevension of Racemization of the chiral Carbon in the Episelenonium Ion Intermediate:steric Protection and Election-withdrawing Effect" Phosphorus Sulphur and Silican. 136,137.138. 649-652 (1998)

    • Related Report
      1998 Annual Research Report
  • [Publications] A.Toshimitsu.S.Uemura: "Organoselenium chemistry.A Practical Approachi" Oxford University Press, 印刷中 (1999)

    • Related Report
      1998 Annual Research Report

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Published: 1997-04-01   Modified: 2016-04-21  

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