Studies on development of the selective oxygenation catalysts based on mimicking function of nonheme monoiron oxygenases

基于模拟非血红素单铁加氧酶功能的选择性加氧催化剂的研制

• 批准号: 12450327
• 负责人: FUNABIKI Takuzo
• 金额: $ 9.41万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450327/
• 关键词: Nonheme Iron Complexes; Oxygenases; Oxygenase-model Catalysts; Dioxygenases; Manganese Complexes; Water-soluble Nonheme Iron Complexes; Oxygenative Cleavage of Aromatics; Oxygen Activation; 酸素モデル触媒; 水溶性ヘム鉄錯体; 3座配位子; α-ケト酸

Following studies were performed on the development of oxygenase-like catalytic functions by nonheme monoiron complexes and manganese complexes and on the clarification of mechanisms of electron transfer that is essential for activation of substrates.1)Intradiol and extradiol oxygenative cleavage of catechols by monoiron complexesCatalytic activity of oxygenations by monoiron complexes ligated by tripodal ligands and tridentate ligands were studied. Effect of electronic and steric effects of substituents on the selective intradiol cleavage gave important information of the oxygen activation and oxygen insertion process into the C-C bonds. In the extraiol cleavage by iron complexes with tridentate ligands also clarified the mechanism of oxygenation via the direct oxygen binding to the iron center. Not only ligands with only the N binding sites but also ligands with N and O binding sites were used for clarification of the O2 insertion into catechols.2)Intra and extradiol oxygenative clea … More vage of catechols by manganese complexesBy mimicking manganese-containing extradiol cleaving oxygenases, Mn(II)-semiquinone complexes were first synthesized. The complexes were found to be oxygenated to give the intradiol cleavage productws. Interestingly, the reversible uptake of oxygen was observed, indicating that the molecular oxygen binds first to the metal center (iron and manganese) prior to binding to the catechol carbon.3)Oxygenations in water by iron complexes with water-soluble ligandsAlthough enzymatic oxygenations proceeds in aqueous media, models oxygenations have been performed in organic solvents. This is partly due to the ligands soluble only in organic solvents, and partly on exclusion of oxygen saurce other than molecular oxygen. We have first developed a model system that works in water to give the selective intradiol cleavage of mono-alkyl catechols, e.g. 4-butyl catechols, catechols with the electron-withdrawing substituents, such as chloro and carboxylate, by using the TPA ligands with sulfonate subsitutients. It is important to find that the protocatechuic acid was found to be oxygenatively cleaved by monoiron complexes, because the model oxygenation has not be developed in spite of the most popular enzyme, protocatechuic oxygenases. It was also found that the pH control of the media is essential for the aqueous system. We also found that the TPA complexes without the solfonate substituents are also effective for the reaction in aqueous media. Less

本论文主要研究了非血红素铁配合物和锰配合物的类加氧酶催化功能及其对底物活化所必需的电子转移机制。1）铁配合物对邻苯二酚的二醇内和二醇外氧化裂解研究了三足配体和三齿配体配位的铁配合物对邻苯二酚氧化反应的催化活性。取代基的电子效应和空间效应对二醇内选择性断裂的影响提供了氧活化和氧插入C-C键过程的重要信息。另外，三齿配体铁配合物的断裂也阐明了氧通过与铁中心直接结合的氧化机制。2）二醇内和二醇外的氧自由基清除作用，以及氧自由基清除作用，均能解释氧自由基在儿茶酚中的插入。 ...更多信息 通过模拟含锰的外二醇加氧酶，首次合成了Mn（II）-半醌配合物。发现该复合物被氧化以得到内二醇裂解产物。有趣的是，观察到氧的可逆吸收，表明分子氧在与邻苯二酚碳结合之前首先与金属中心（铁和锰）结合。3）铁与水溶性配体的络合物在水中的氧化虽然酶促氧化在水介质中进行，但模型氧化已经在有机溶剂中进行。这部分是由于配体仅溶于有机溶剂，部分是由于排除了除分子氧之外的氧源。我们首先开发了一个在水中工作的模型系统，通过使用具有磺酸酯取代基的TPA配体，给出单烷基儿茶酚，例如4-丁基儿茶酚，具有吸电子取代基（如氯和羧酸酯）的儿茶酚的选择性二醇内裂解。重要的是发现原儿茶酸被发现被一价铁络合物氧化裂解，因为尽管最流行的酶原儿茶加氧酶，模型氧化还没有被开发。还发现，介质的pH控制对于水性系统是必不可少的。我们还发现，没有磺酸盐取代基的TPA配合物在水介质中也是有效的反应。少