Determination of Transition Structure Geometries for Reactions at Nonstereogenic Atoms

在有机动力学计划的支持下，Beak博士将利用“内环限制测试”来研究在没有立体化学特征的原子上发生的反应的允许几何形状。在该方法中，在成键基团和离开基团通过链连接的系统中执行非立体生成杂原子的转移。分子内转移所需的内环的大小限制了可用的反应几何构型。当与其他机械工具结合使用时，这种方法的应用应该提供关于原子转移反应中过渡态几何的重要、详细的信息。我们将研究氧、氮、卤素、硫和氢气中反应的几何构型。涉及协调、联合和/或分离步骤的机制将针对每一案例进行评估。其他机制探针，例如交叉实验、动力学研究和分子内和分子间同位素效应的测定，将用于补充通过应用内环限制试验获得的结果。

With support from the Organic Dynamics Program, Dr. Beak will utilize the "endocyclic restriction test" to investigate allowed geometries for reactions that occur at atoms which lack stereochemical features. In this approach, transfer of non-stereogenic heteroatoms is performed in systems wherein the bond forming group and the leaving group are joined by a chain. The size of the endocyclic ring required for intramolecular transfer limits the available reaction geometry. When taken in combination with other mechanistic tools, application of this approach should provide important, detailed information regarding the geometry of the transition states in atom-transfer reactions. The geometries of reactions at oxygen, nitrogen, halogen, sulfur, and hydrogen will be investigated. Mechanisms involving concerted, associative and/or dissociative steps are to be evaluated for each case. Other mechanistic probes, e.g., crossover experiments, kinetic studies, and determinations of intra- and intermolecular isotope effects, will be used to supplement results obtained via application of the endocyclic restriction test.