Vitamin B
12-dependent enzymes, involving the cobalt species as a catalytic center, mediate various isomerization reactions accompanied by carbon-skeleton rerragements. In order to simulate the catalytic functions of vitamin B
12 as excerted in the hydrophobic active sites of enzymes concerned, we have been dealing with hydrophobic vitamin B
12 derivatives which have ester groups in place of the peripheral amide moieties of the naturally occurring vitamin B
12. In this work, the carbon-skeleton rearrangements as mediated by hydrophobic vitamin B
12 derivatives were investigated under elec-trochemical conditions. The controlled-potential electrolyses of alkyl halides with various electronwithdrawing 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-expansin reactins. 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 B
12. The migration of the pheny group was observed under the conditions forming a radical intermediate. The ester-migrated product was detected under the conditions forming an anionic intermediate. This is the first successful example in selecting a migrating group by electroylsis potential. We have also prepared a strapped hydrophobic vitamin B
12 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 was carried out. The simple hydrophobic vitamin B
12 tends to bind
S-enantiomers more favorably. On the other hand, strapped hydrophobic vitamin B
12 acts to bind
R-enantiomers more favorably. These results suggested that the stability of alkylated complexes was dominated the enantioselectivity of reduction products.
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