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.
