• Title/Summary/Keyword: chiral auxiliary

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Chiral Molecular Recognition by Alkoxy-amine-aluminum Derivatives (Alkoxy-amine-aluminum 유도체에 의한 키랄 분자 인식)

  • Kim, Jong-Mi
    • Journal of the Korean Society of Industry Convergence
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    • v.12 no.3
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    • pp.143-147
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    • 2009
  • The enantioselective reduction of representative prochiral alkyl-aryl ketones with a new chiral alkoxy-amine-aluminum derivatives from aluminum hydride and ${\alpha},{\alpha}$-diphenyl-${\beta}$-amino alcohols, such as (S)-(-)-2-amino-3-methyl-1,1-diphenylbutan-1-ol(AMDPB) and (S)-(-)-2-(diphenylhydroxy-methyl)pyrrolidine(DPHMP), in THF at $0^{\circ}C$ was studied. In the reduction of alkoxy-amine-aluminum derivatives, acetophenone, propiophenone, isopropiophenone, and butyrophenone are reduced to corresponding aromatic secoundary alcohols with 34~60 % enantiomeric excess of (S)-isomers. For such ketones, the optical induction was enhanced by increasing a size of alkyl groups.

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Diastereoselective Synthesis of (+)-Frontalin

  • Jung, Jung-Hwa;Kim, Hee-Doo
    • Proceedings of the PSK Conference
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    • 2002.10a
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    • pp.345.3-346
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    • 2002
  • In connection with the asymmetric synthesis of chiral l.2-diol. we report here the total synthesis of (+)-frontalin using diastereoselective alkylation featuring tridentate chelation-controlled asymmetric alkylation of a-hydroxyketone, in which the chiral auxiliary is attached to the hydroxyl group as ether linkage. The starting D-glyceraldehyde acetonide was converted (S)- [(4R)-2.2-dimethyH,3-dioxolan-4-yl] (4-methoxyphenyl) methanol. (omitted)

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Highly Diastereoselective Aldol-Type Reaction Using 3-Acetylthiazolidine-2-thione (3-아세틸티아졸리딘-2-티온을 이용한 입체선택적인 알돌-축합반응)

  • Tae Myeong Jeong;Ki Hun Park
    • Journal of the Korean Chemical Society
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    • v.33 no.4
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    • pp.426-430
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    • 1989
  • Amino alcohol-derived thiazolidinethiones [4-(S)-IPTT, 4(S)-ETT] serve as efficient chiral auxiliary in tin medicated aldol condensation. A highly enantioselective aldol-type reaction forming various ${\beta}$-hydroxy carbonyl compounds from 3-acetylthiazolidine-2-thione and achiral aldehyde is achieved via divalent tin enolate. The other advantages of these chiral auxiliaries were the ease of removal by methanolysis.

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Synthesis of Azabicyclo[3.2.1]octane Skeleton of Tropane Alkaloid (트로판 알칼로이드의 아자비시크로[3.2.1]옥탄 골격합성)

  • Suh, Young-Ger;Choi, Young-Gi;Jung, Jae-Kyung;Min, Kyung-Hoon
    • YAKHAK HOEJI
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    • v.41 no.1
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    • pp.18-21
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    • 1997
  • Synthesis of an optically active azabicyclo[3.2.1]octane skeleton as a backbone of the tropane alkaloids has been achieved by employing intramolecular Mannich reaction. Utilizat ion of (R)-${\alpha}$-methylbenzylamine as a chiral auxiliary provided an excellent cyclization of amino dioxolane precursor. However, this auxiliary did not afford high asymmertic induction for the preparation of the optically active cyclization precursor.

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Studies Directed Toward Asymmetric Total Synthesis of Calycotomine (Calycotomine의 입체선택적 합성 연구)

  • Yang, Jung-Eun;Jung, Jae-Kyung
    • YAKHAK HOEJI
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    • v.53 no.3
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    • pp.161-164
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    • 2009
  • Synthetic studies directed toward an asymmetric total synthesis of calycotomine, an representative tetrahydroisoquinoline, are described. The application of N-tert-butane sulfinyl chiral auxiliary to the Pictet-Spengler type reaction for the efficient synthesis of tetrahydroisoquinoline skeleton has been also investigated.