• Title/Summary/Keyword: Stereochemistry

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Effect of Trialkylborane on the Stereochemistry of Ketone Reduction with Lithium Borohydride

  • Nung-Min Yoon;Jin-Soon Cha;Won-Suh Park
    • Bulletin of the Korean Chemical Society
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    • v.4 no.1
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    • pp.14-17
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    • 1983
  • The effects of trialkylborane on the stereochemistry of ketone reduction with lithium borohydride were studied for the four representative ketones, namely 4-t-butylcyclohexanone, 2-methylcyclohexanone, norcamphor, and camphor. The presence of trialkylborane increased the yields of the less stable alcohols. For example, in the presence of tri-s-butylborane, 42 % yield of cis-4-t-butylcyclohexanol was observed whereas only 8 % yield with lithium borohydride alone in the reduction of 4-t-butylcyclohexanone. The in situ formation of lithium trialkylborohydride, by the hydride transfer from lithium trialkoxyborohydride to trialkylborane, was demonstrated as a possible mechanism for the catalytic effect of trialkylborane.

입체화학을 이용한 생분해성 고분자인 폴리유산의 스트레오 콤플렉스 형성 조절 및 특성연구

  • Lee, Won-Gi
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 2007.05a
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    • pp.558-560
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    • 2007
  • l-PLA와 d-PLA사이의 complex형성은 화학 양론적으로 동일 몰비에서 강력한 상호 작용력에 기인한다. 이러한 특성을 이용하여 PLA블렌드 계에서 stereochemistry를 이용하여 블렌드 한 성분에 defect를 부여함으로서 complex정도를 조절함으로서 다성분 고분자계의 표면 조성의 조절(표면 물성의 조절)과 생분해성의 조절이 가능함을 보였다.

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Gossypiline, a New Lignan from Jatropha gossypifolia

  • Das, R.;Das, B.;Kashinatham, A.
    • Natural Product Sciences
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    • v.4 no.4
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    • pp.238-240
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    • 1998
  • A new lignan, gossypiline (1) has been isolated from the aerial parts of Jatropha gossypifolia. The structure of 1 was established from its spectral data. The conversion of isogadain, a known lignan, to 1 confirmed the structure as well as the stereochemistry of 1.

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Cycloaddition Reaction on 1,4,5,8-Tetraazaphenanthrene Photoexcited Triplet State to Some Olefins

  • Park, Seung-Ki;Shim, Sang-Chul
    • Bulletin of the Korean Chemical Society
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    • v.8 no.1
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    • pp.27-30
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    • 1987
  • Photocycloaddition of 1,4,5,8-tetraazaphenanthrene to olefins proceeds through a biradical triplet-state intermediate as proven by the photoproduct stereochemistry, quantum yield measurements, sensitization, quenching, and fluorescence and phosphorescence quenching studies.

Diastereoselectivity in the Reaction of 2-Piperidineacetates

  • 정현규;김형우;정규현
    • Bulletin of the Korean Chemical Society
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    • v.20 no.3
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    • pp.325-328
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    • 1999
  • In the reactions of the enolates of various 2-piperidineacetates with iodomethane or trisyl azide, the anti isomer was always predominant over the syn one, independent of the stereochemistry of the piperidineacetates. The piperidineacetates having OTBDMS moiety at C5 proceeded more diastereoselectively than the compounds without the substituent. The diastereoselectivity could be explained by perpendicular model for the electrophilic substitution reaction.