Mechanistic Studies on Halodiazirines, Radical Stabilization by meta Substituents

圣母大学的泽维尔·克里里的这一项目得到了有机动力学项目的支持，该项目涉及对某些有机反应的详细分子途径的研究。我们将研究一类被称为溴二氮杂环的化合物与负离子的反应，在该项目的第二部分中，将检查自由基的稳定性。该程序将提供有关有机反应如何在分子水平上进行的有用信息。这项研究是基于这样一种信念，即人们普遍接受的溴二氮杂环与亲核试剂反应的机理是不正确的。提出了一种新的N-叠氮二氮杂环己烷作为溴苯基二叠氮烷与叠氮离子反应的中间体。然而，在亲核试剂是高度极化的情况下(例如，硫代苯氧化物)，电子转移可能成为首选途径。将进行N-15标签实验，以区分各种机械可能性。我们将加深对取代反应的理解，并对控制直接亲核攻击和电子转移的因素有深入的了解。还将生成N-叠氮胺，并将调查影响其稳定性的因素。在这项工作的第二部分，提出了一种新的、以前未被认识的间位取代基稳定自由基的机制。将尝试通过使用巴黎圣母院小组开发的亚甲基环丙烷重排探针来实验验证这一假设。这些研究将加强对有助于自由基稳定性的因素的了解。

This project by Xavier Creary of the University of Notre Dame is supported by the Organic Dynamics Program, and is involved in a study of the detailed molecular pathway of certain organic reactions. The reaction of a class of compounds known as bromodiazirines with negative ions will be studied, and in a second part of the project, free radical stabilities are to be examined. This program will provide useful information about how organic reactions proceed on a molecular level. This study is based on the belief that the commonly accepted mechanism of the reaction of bromodiazirines with nucleophiles cannot be correct. A novel N-azidodiazirine is proposed as an intermediate for the reaction of bromophenyldiazirine with azide ion. However, in cases where the nucleophile is highly polarizable (e.g., thiophenoxide), electron transfer may become the preferred pathway. N-15 labeling experiments will be carried out to distinguish among the various mechanistic possibilities. Understanding of substitution reactions will be advanced and insights should be gained into the factors controlling direct nucleophilic attack vs. electron transfer. N-azidoamines will also be generated and factors that affect their stability will be investigated. In a second part of this work, a novel and previously unrecognized mechanism by which meta substituents can stabilize free radicals is proposed. Attempts will be made to verify this hypothesis experimentally by using the methylenecyclopropane rearrangement probe developed by the Notre Dame group. These studies will enhance the state of understanding of factors that contribute to free radical stability.