Spontaneous oxidative cyclisations of 1,3-dihydroxy-4-dimethylallylnaphthalene to tricyclic derivatives.

Attachment of a dimethylallyl moiety to C4 of 1,3-dihydroxynaphthalene led to spontaneous oxidative cyclisations, resulting in the formation of two tetrahydrobenzofuran and one bicyclo[3.3.1]nonane derivatives. Incubation with 18O-enriched atmosphere proved that both of the incorporated oxygen atoms were originated from O2. A radical-involved mechanism was proposed for the cyclisations.