Organic Synthesis Catalyzed by Cobalt Complexes with Co-C Bond

Co-C键钴配合物催化有机合成

基本信息

批准号：
07651034
负责人：
HISAEDA Yoshio
金额：
$ 1.34万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Vitamin B12-dependent enzymes, involving the cobalt species as a catalytic center, mediate various isomerization reactions accompained by carbon-skeleton rearrangements. In this reaction, cobalt-alkyl complex is a key intermediate. In order to simulate the catalytic functions of vitamin B12 as excerted in the hydrophobic active sites of enzymes concerned, we have been dealing with hydrophobic vitamin B12 derivatives which have ester groups in place of the peripheral amide moieties of the naturally occurring vitamin B12. In this work, the carbon-skeleton rearrangements which was applied to the ring-expansion reactions as mediated by hydrophobic vitamin B12 derivatives were investigated under electrochemical conditions.The electrolysis of alicyclic ketones (5,6,7, and 8-membered rings) with a carboxylic ester and a bromomethyl group was carried out in N,N-dimethylformamide in the presence of a catalytic amount of hydrophobic vitamin B12. The ring-expansion reaction largely proceeded at -2.0 V vs.SCE for all the substrates. ESR study showed that the reaction proceed through radical intermediates.We also tried to synthesize a new organometallic catalyst with a cobalt-alkyl complex. An alkylated complex having a cobalt-carbon bond gives an alkyl radical by photolysis. If a dicobalt complex is used, it will give a cyclic compound as a coupling compound of biradical after photolysis. This study focused on developing a new catalyst for prepareing a cyclic copmpound. A new dinucleating ligand, which has schiff base unit liked each other with an ethylene apacer, was synthesized by one-pot reaction of salicylaldehyse, ethylenediamine, and methylenebis (4,4'-salicylaldehyde).

维生素B12依赖性酶，涉及钴物种作为催化中心，介导了各种异构反应，伴随着碳骨骼重排。在此反应中，钴 - 烷基复合物是关键的中间体。为了模拟有关酶的疏水活性位点的维生素B12的催化功能，我们一直在处理疏水性维生素B12衍生物，这些疏水性维生素B12衍生物具有酯基，代替了发生自然存在的维生素B12的外周酰胺部分。 In this work, the carbon-skeleton rearrangements which was applied to the ring-expansion reactions as mediated by hydrophobic vitamin B12 derivatives were investigated under electrochemical conditions.The electrolysis of alicyclic ketones (5,6,7, and 8-membered rings) with a carboxylic ester and a bromomethyl group was carried out in N,N-dimethylformamide in the presence of催化量的疏水维生素B12。所有底物的环膨胀反应在-2.0 V vs.sce上进行。 ESR研究表明，反应通过自由基中间体进行。我们还试图将新的有机金属催化剂与钴 - 烷基复合物合成。具有钴碳键的烷基化络合物通过光解会产生烷基自由度。如果使用了二核络合物，它将给出循环化合物作为光解后Biradical的耦合化合物。这项研究的重点是开发一种新的催化剂，以准备循环共培养。一种具有Schiff碱基单元的新核配体与乙烯辅助剂相互喜欢，是通过AlicyLaldehyse，乙二胺和甲基苯甲比（4,4'-甲基甲醛）的一锅反应合成的。