ORGANOMETALLIC MODELS FOR B12 CATALYZED REACTIONS

B12 催化反应的有机金属模型

• 批准号: 3292536
• 负责人: JOHN W SUGGS
• 金额: $ 6.82万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-07-01 至 1989-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3292536
• 关键词: 1 carbon compound; allosteric site; catalyst; chelating agents; chemical binding; chemical reaction; ligands; organometallic compounds; phenanthrolines; vitamin B12 coenzyme

Reactions mediated by the coenzyme B12 are not only important for the maintenance of human health, they are some of the most unusual chemical transformations known. Previous work has suggested that B12 catalyzed reactions are initiated by homolysis of a cobalt-carbon bond. However, in the absence of protein and substrate the cobalt-carbon bond in B12 is reasonably stable. Our goal is to prepare systems which mimic this substrate-induced homolysis of a metal-carbon bond. The effect of the substrate in B12 systems is one example of an allosteric effect, so that our proposed work should shed light on the general problem of the mechanisms, at the molecular level, of allosteric effects. The particular system on which attention will be focused will be orthometalled derivatives of 2-phenyl-1,10-phenanthroline. Transition metals react with this ligand (and its derivatives) to form tridentate N,N,C chelates. In these complexes the phenyl ring is kept in the plane of the 1,10-phenanthroline ring by the metal carbon bond. Metal-binding groups will be placed on the ortho position of the metallated phenyl ring so that upon addition of a metal ion (such as Mg++) a torque will be induced, breaking the metal-carbon bond. Thus, this system will model how substrate binding can promote M-C homolysis. The chemistry of these M-C diradicals will be studied to see if they can carry out the same rearrangements as B12 based enzymes.

由辅酶 B12 介导的反应不仅对 维护人类健康，它们是一些最不寻常的化学物质 已知的变换。 先前的工作表明 B12 催化 反应由钴-碳键的均裂引发。 然而，在 由于缺乏蛋白质和底物，B12 中的钴碳键是 相当稳定。 我们的目标是准备模仿这一点的系统 底物诱导的金属-碳键均裂。 的效果 B12 系统中的底物是变构效应的一个例子，因此 我们提议的工作应该能够阐明该领域的普遍问题 分子水平上的变构效应机制。 将关注的特定系统将是 2-苯基-1,10-菲咯啉的邻位金属衍生物。 过渡 金属与该配体（及其衍生物）反应形成三齿 N,N,C 螯合物。 在这些配合物中，苯环保持在平面上 1,10-菲咯啉环通过金属碳键形成。 金属结合 基团将位于金属化苯环的邻位上 因此，添加金属离子（例如 Mg++）后，扭矩将为 诱导，破坏金属-碳键。 因此，该系统将模拟如何 底物结合可以促进 M-C 均裂。 这些 M-C 的化学性质 将研究双自由基，看看它们是否可以执行相同的操作 重排为基于 B12 的酶。