Irradiation of 3-(alkenyloxy) phenols and 1-(alkenyloxy)-3-(alkyloxy) benzene derivatives, at λ= 254 nm in acidic media, yields benzocyclobutenes, 3-alkylphenols, 3-alkylanisols, and 4- alkyl-1, 2-dialkyloxybenzenes depending on the substitution pattern of the aromatic ring and the olefinic side chain. The final products are derived from an intramolecular [2+ 2] photocycloaddition and acidic rearrangements from a common intermediate.
