New photochemical rearrangements and extrusion reactions of aromatic compounds induced by an intramolecular [2+2] photocycloaddition between a naphthalene and a resorcinol moiety

An intramolecular [2+2] photocycloaddition between a naphthalene and a resorcinyl moiety was followed by an acid catalyzed rearrangement leading to tricyclic tetrahydrofuran derivatives. The reaction was efficient when the irradiation was carried out at 300 nm. For the first time, an extrusion of a RCOCH3 (R=H or alkyl) fragment from the tetrahydrofuran ring was observed when the tricyclic tetrahydrofuran derivatives were irradiated at 254 nm. Reaction rate and yield depended on the substitution pattern. In particular, significantly different quantum yields were measured in the case of different diastereoisomers.