The photoaddition reactions of various alkenes with 10-methylacridinium ion occur efficiently in methanol to yield the adducts in which the methoxy group from methanol is generally introduced in the less substituted sp2 carbon under irradiation of the visible light. In the case of photochemical reaction of cyclohexene with AcrH+, however, cyclohexene adduct with no incorporation of methoxy group from methanol was obtained as well as the methoxy-incorporated adduct. When a sterically hindered alkene, 2,3-dimethylbut-2-ene is employed, no methoxy group is incorporated in the adduct. On the other hand, the photoaddition of but-2-ene affords two regioisomers, the ratio of which varies slightly depending on the cis- and trans-isomers as well as reaction temperature. The reaction mechanism involving photoinduced electron transfer from alkenes to the singlet excited state of 10-methylacridinium ion provides a comprehensive and confirmative basis for understanding the product distributions, the fluorescence quenching by alkenes, and the dependence of quantum yields on the alkene concentrations.
|Number of pages||7|
|Journal||Journal of the Chemical Society. Perkin Transactions 2|
|State||Published - 1993|