Photochemical reactions of aromatic compounds. Part XX. Photocycloaddition of 9-cyanoanthracene to furan and mono- and dimethyl-furans

Abstract

Photoreaction of 9-cyanoanthracene (1) with furan (2a), and with 2-methyl-(2b), 3-methyl-(2c), and 2,5-dimethyl-furan (2d) affords the (4 + 4) cycloadducts, 9-cyano-9,10,11,13-tetrahydro-9,10[2′,5′]-furanoanthracene (5a) and its methyl substituted derivatives (5b–d), respectively, in good yields. Irradiation of (1) in the presence of thiophen (3) or 1-methylpyrrole (4) gives no cycloadduct. An exciplex mechanism is suggested for these reactions on the basis of fluorecence measurements and kinetics.