Electroorganic Synthesis Mediated by Metalloenzyme Models

金属酶模型介导的有机电合成

基本信息

批准号：
09450333
负责人：
HISAEDA Yoshio
金额：
$ 8.64万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

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.

在这项工作中，在电化学条件下研究了由疏水维生素B12衍生物介导的碳骨骼重排。烷基卤化物的受控电势具有各种电子与绘图组，并通过形成阴离子中间体的形成，有效地进行了电化学碳骨骼重排。这些反应也可以应用于环膨胀反应。在存在催化量的疏水性维生素B12的情况下，我们对β-碳原子上的烷基卤化物进行电解。在形成自由基中间体的条件下观察到苯基的迁移。在形成阴离子中间体的条件下检测到酯迁移的产品。这是通过电解潜力选择迁移组的第一个成功示例。我们还准备了绑带的疏水性维生素B12，以改变对映选择性。进行了同一碳原子上具有苯基，方法和羧基基团的外消旋烷基卤化物的受控电力电解。简单的疏水性维生素B12倾向于更有利地结合S-Anantiomers。另一方面，绑扎的疏水性维生素B12起着更有利的R-替代物的作用。这些结果表明，烷基化络合物的稳定性以还原产物的对映选择性为主。我们准备了用沙龙型配体的催化剂的双ob-cobalt复合物。当在BIS -Cobalt复合物存在下以-1.4 V进行苄基溴的电解时，主要产物为Bibenzyl。该结果表明，双粘体配合物将是二聚反应的极好催化剂。