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Part I. Molecular Basis of Remote Non-Bonding Interaction for the Enantioselective Lipase-Catalyzed Reactions : Part II. Stereoselective Synthesis of Polyhydroxylated Alkaloids from Chiral Aziridine 원문보기

  • 저자

    Eum, Heesung

  • 학위수여기관

    韓國外國語大學校 大學院

  • 학위구분

    국내박사

  • 학과

    화학과

  • 지도교수

    하현준

  • 발행년도

    2014

  • 총페이지

    175 p

  • 키워드

    aziridine lipase alkaloid stereoselective synthesis enantioselective non-bonding interaction;

  • 언어

    eng

  • 원문 URL

    http://www.riss.kr/link?id=T13538783&outLink=K  

  • 초록

    Part I. Molecular Basis of Remote Non-Bonding Interaction for the Enan-tioselective Lipase-Catalyzed Reactions Burkholderia cepacia lipase (BCL) shows high enantioselectivity toward chiral primary alcohols, but this enantioselectivity is often unpredictable, especially for substrates that contain an oxygen at the stereocenter. For example, BCL resolves β-substituted-γ-acetyloxymethyl-γ-butyrolactones (acetates of a chiral primary alcohol) by hydrolysis of the acetate, but the enantioselectivity varies with nature and orientation of the β-alkyl substituent. To rationalize this unusual selectivity, we used combination of experiments that show the importance of polar interactions and modeling to reveal differences in orientations of the enantiomers. The ability to rationalize enantioselectivity in this difficult case demonstrates the importance of including umbrella-like orientations of the slow enantiomer in modeling enantioselective interactions. CAL-B catalyzed desymmetrization of prochiral 3-alkylglutaric acid diesters was performed for the preparation of optically active 3-alkylglutaric acid monoesters bearing various alkyl substituents, including methyl, ethyl, propyl and allyl. Allyl esters showed far better stereoselectivity among many alkyl esters implying possible π - π interaction between the olefin of the sub-strate and the side chains of Trp104 or His224 at the active site of the enzyme.Part II. Stereoselective Synthesis of Polyhydroxylated Alkaloids from Chi-ral Aziridine Highly stereoselective dihydroxylation of the chiral 3-(aziridine-2-yl)acrylate afforded a new general method for the synthesis of 1,3,4-trihydroxy-2-amines. By using this reaction as a key step, two natural products, calyculin fragment C33-C37 and 1,4-dideoxy-1,4-imino-L-ribitol, were synthesized without requisition of any protection steps. Another biologically active trihydroxyamino compounds, hyacinthacine A1 and its analogues which is pol-yhydroxylated pyrrolizidine alkaloids were also synthesized in stereoselective manner via regioselective aziridine ring-opening reaction.


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