SYNTHESIS OF VITAMIN B12 MODELS

维生素B12以其辅酶的形式存在，是一系列维生素B12的辅因子。 11种酶催化转化。 其中，三种酶： β-甲基天冬氨酸酯、甲基丙二酰-SCoA和甲基衣康酸酯 变位酶特别令人感兴趣，因为它们催化碳骨架 在有机化学中没有类似物的重排 化学. 此外，在该系列中有四种氨基变位酶， 也缺乏良好的先例。 本文提出了化学非酶模型 反应将被探索，目的是解开的机制， 维生素B12的作用。 新的模型旨在探索氢提取，新的模型， 氨基天冬氨酸和β-甲基天冬氨酸重排将被 考察 衣康酸甲酯的~（13）C标记研究 将进行重新安排。 将特别致力于 进一步发展质谱法作为烷基 钴胺素系列 自由基中间体的可能中间性 将使用模型进行探索。 的立体化学研究 将进行衣康酸甲酯催化的重排。

Vitamin B12, in the form of its coenzyme, is a cofactor in a series of eleven enzyme-catalyzed transformations. Of these, three enzymes: Beta-methylaspartate mutase, methylmalonyl-SCoA mutase and methylitaconate mutase are of special interest because they catalyze carbon-skeleton rearrangements for which there have been no analogues in organic chemistry. In addition, there are four amino mutases in this series which also lack good precedent. In this proposal, chemical nonenzymic model reactions will be explored with the aim of unravelling the mechanism of action of vitamin B12. New models designed to explore the hydrogen abstraction, and new models for the amino mutase and Beta-methylaspartate mutase rearrangements will be examined. Carbon-13 labelling studies of the methylitaconate mutase rearrangement will be carried out. Special effort will be devoted to the further development of mass spectrometry as an analytical tool in the alkyl cobalamin series. The possible intermediacy of free radical intermediates will be explored using models. Stereochemical studies of the methylitaconate mutase catalyzed rearrangement will be conducted.