Hydrophobic vitamin B12. Part 13. Asymmetric reaction of hydrophobic vitamin B12 under electrochemical conditions and rationalization of enantioselectivity based on conformational analysis

Teruhisa Ohno, Takuya Nishioka, Yoshio Hisaeda, Yukito Murakami

    研究成果: ジャーナルへの寄稿学術誌査読

    16 被引用数 (Scopus)

    抄録

    The controlled-potential electrolysis of racemic ethyl 3-bromo-2-methoxy-2-phenylpropionate was carried out at -1.8V vs. SCE in N,N-dimethylformamide, as mediated by a simple hydrophobic vitamin B12, [Cob(II)7C3ester]ClO4, and a strapped hydrophobic vitamin B12, [Cob(II)(c,10-PDA)6C3ester]ClO4, to afford ethyl 2-methoxy-2-phenylpropionate and ethyl 2-methoxy-3-phenylpropionate in the dark. The simple hydrophobic vitamin B12 acted to afford ethyl (S)-2-methoxy-2-phenylpropionate, the hydrogen-substituted product, in 55% e.e., while the strapped hydrophobic vitamin B12 was in favor of formation of the corresponding R enantiomer in 26% e.e. Since the reaction proceeds via formation of an intermediate in which the ethyl 2-methoxy-2-phenylpropionate moiety is bound to the hydrophobic vitamin B12, the chiral microenvironment provided by the peripheral groups placed around the corrin framework is responsible for the enantioselective formation of the alkylated hydrophobic vitamin B12. The enantioselective coordination of the substrate species was rationalized by means of molecular mechanics and dynamics computations as well as by Monte Carlo conformational search; the simple hydrophobic vitamin B12 with the S substrate is lower in energy than the complex with the R substrate by l.8 kJ mol-1, while the strapped hydrophobic vitamin B12 with the R substrate is lower than the identical complex with the S substrate by 2.0 kJ mol-1.

    本文言語英語
    ページ(範囲)207-218
    ページ数12
    ジャーナルJournal of Molecular Structure: THEOCHEM
    308
    C
    DOI
    出版ステータス出版済み - 5月 10 1994

    !!!All Science Journal Classification (ASJC) codes

    • 生化学
    • 凝縮系物理学
    • 物理化学および理論化学

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