1999 Fiscal Year Final Research Report Summary
Electroorganic Synthesis Mediated by Metalloenzyme Models
| Project/Area Number |
09450333
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
有機工業化学
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
HISAEDA Yoshio Graduate School of Engineering, Kyushu University, Professor, 大学院・工学研究科, 教授 (70150498)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMAKOSHI Hisashi Graduate School of Engineering, Kyushu University, Research Associate, 大学院・工学研究科, 助手 (00284539)
HAYASHI Takashi Graduate School of Engineering, Kyushu University, Associate Professor, 大学院・工学研究科, 助教授 (20222226)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Hydrophobic vitamin B12 / Electro-organic synthesis / Carbon-skeleton rearrangements / Radical intermediate / Anion intermediate / Strapped hydrophobic vitamin B12 / Bis-cobalt complex / Dimerization reaction |
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| Research Abstract |
In this work, the carbon-skeleton rearrangements as mediated by hydrophobic vitamin B12 derivatives were investigated under electrochemical conditions. The controlled-potential electrolyses of alkyl halides with various electron-withdrawing groups were carried out, and the electrochemical carbon-skeleton rearrangements proceeded effectively via formation of anionic intermediates. These reactions can be also applied to the ring-expansion reactions. We have carried out the electrolysis of an alkyl halide having two ester groups and one phenyl group on the β-carbon atom in the presence of a catalytic amount of the hydrophobic vitamin B12. The migration of the pheny group was observed under the conditions forming an radical intermediate. The ester-migrated product was detected under the conditions forming anionic intermediate. This is the first successful example in selecting a migrating group by electrolysis potential. We have also prepared a strapped hydrophobic vitamin B12 in order to change the enantioselectivity. The controlled-potential electrolysis of a racemic alkyl halide having phenyl, methoxy, and carboxylic ester groups on the same carbon atom were carried out. The simple hydrophobic vitamin B12 tends to bind S-enantiomers more favorably. On the other hand, strapped hydrophobic vitamin B12 acts to bind R-enantiomers more favorably. These results suggested that the stability of alkylated complexes was dominated the enantioselectivity of reduction products.
We prepared bis-cobalt complex with salen-type ligand for the catalyst. When electrolysis of benzyl bromide was carried out at - 1.4 V vs. SCE in the presence of the bis-cobalt complex, major product was bibenzyl. This result suggests that the bis-cobalt complex will be an excellent catalyst for dimerization reactions.
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