Photochemical 2+2 Cycloaddition of 3-Methyl-2-cyclohexen-1-one to C_(70) Fullerene

摘要

Since their discovery in 1985 by Kroto,Smalley and co-workers,fullerenes have been the subject of innumerable studies,including those examining their photochemical reactivity.Photochemical [2+2] cyclo-addition reactions involving alpha,beta-unsaturated ketones (enones) and C_(60) fullerene are well documented.It has been found that this reaction is quite general,as a large variety of cyclic enones engage in photocycloaddition across the most reactive 6,6-bond of the C_(60) molecule when subjected to wavelengths of light in the UV region (ca.300 nm).Mixtures of isomeric products are obtained depending on the enone used in the reaction.Such reactions are thought to take place via a mechanism similar to that for photoaddition of enones to ordinary alkenes in the presence of UV light,involving the addition of enone triplet excited states to ground state alkenes via 1,4-biradical intermediates.