Photochemical Reactions of Aromatic Compounds. XXXIII. Photoreactions of 1-Cyanonaphthalene with Indene in Various Solvents

Article abstract of DOI:10.1246/bcsj.53.502

The stereospecific photocycloaddition of 1-cyanonaphthalene to indene occured in cyclohexane, benzene, diethyl ether, tetrahydrofuran, and ethyl acetate, giving the endo head-to-head cycloadduct as the sole 1:1-adduct.The mechanism was discussed in terms of the exciplex intermediacy.In methanol or in acetonitrile in the presence of water, the photoreaction gave the dihydrocycloadduct (8), accompanied by the formation of 2-methoxyindan and 2,2'-dimethoxy-1,1'-biindanyl or 2-indanol and 1-hydroxy-2,2'-biindanyl.In these solvents, the reactions were suggested to beinitiated by photochemical electron transfer; the methoxylated or hydroxylated compounds are formed by the nucleophilic attack of methanol or water on the indene cation.Anionic species, including the 1-cyanonaphthalene anion, were suggested to play important roles in the formation of 8.