Reaction of Cyclohexene with Iodosylbenzene Catalyzed by Non-Porphyrin Complexesof Iron(III) and Aluminum(III). Newly Discovered Products and a New Mechanistic Proposal

摘要

Iodosylbenzene has been widely used as a source of oxygen atoms in metal-catalyzed oxygenation reactions. Until recently, it has been widely assumed that such reactions proceed exclusively via high-valent metal oxo intermediates. However, the recent discovery that olefin epoxidations by iodosylbenzene may be catalyzed by certain nonredox metal complexes incapable of forming high-valent metal oxo complexes indicates that additional pathways for these oxygen-transfer reactions must exist. Iodine(III) compounds are known to react with olefins in the absence of metal catalysts, although epoxides have never been reported as products. Nevertheless, the possibility, originally proposed by Moriarty et al., that metal-catalyzed reactions of iodosylbenzene with olefins may involve I containing intermediates wherein I, rather than oxygen or the metal, is the electrophilic center must be considered. We report here studies of reactions of iodosylbenzene with olefins in the presence of complexes of salts of Fe and Al. We find products, in addition to epoxides, whose presence suggests strongly that the mechanisms of these reactions are related to those occurring between olefins and soluble I.