217472-84-9

Photochemical reactions of methyl 3-(o-alkylphenyl)-2,2-dimethyl-3- oxopropanoates in hexane gave only the corresponding benzocyclobutenols. However, when irradiation was carried out in methanol, 3-oxonaphthalenones were produced together with the benzocyclobutenols. The ratio of benzocyclobutenol to naphthalenone depends on the bulkiness of the alkyl group in the ortho position. Intermediary 1,4-diradicals or dienols were efficiently trapped by oxygen to afford the corresponding peroxides and/or oxygenated compounds derived from the peroxides.