Ruthenium-Promoted Radical Addition Reactions to Arenes

Arenes have been shown to be activated by transition metals toward nucleophilic attack by radicals. The goal of this research was to determine whether or not the organometallic group cyclopentadienylruthenium would alter the reactivity of the complexed arene 1,2-dihydronapthalene to the extent that it could undergo nucleophilic radical addition reactions. This project also focused on creating addition products with high diastereoselectivity. It was predicted that cyclopentadienylruthenium would effectively activate 1,2-dihydronapthalene and create products with high diastereoselectivity. Radical additions of a cyclohexyl group, an isopropyl group and an octyl group were attempted in order to determine the ability of (1,2-dihydronapthalene)cyclopentadienylruthenium to undergo nucleophilic attack. Additions of the cyclohexyl and isopropyl groups were successful using tris(trimethylsilyl)silane in the presence of azobisisobutyronitrile in refluxing 1,2-dichloroethane. The cyclohexyl group addition provided evidence that the reaction resulted in high diastereoselectivity. Only a trace amount of the octyl addition product was formed. Purification of the addition products was complicated by the similar polarities of the products and the starting material. Analysis of the addition products was performed using LC/MS, HRMS and NMR.