Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Tetraphenylporphine‐sensitized photooxygenation of benzofuran derivatives <jats:bold>1</jats:bold> afforded the corresponding benzofuran dioxetanes <jats:bold>2</jats:bold> in good yields. Allylic hydroperoxides <jats:bold>3</jats:bold> were formed regioselectively from 2,3‐dimethyl‐substituted benzofurans as minor products, except in the case of the benzofuran <jats:bold>1d</jats:bold>, which gave predominantly the hydroperoxide <jats:bold>3d</jats:bold>. The relative reactivities of the benzofurans toward singlet oxygen depended on the nature of substituents at the C‐2 and C‐3 positions of the furan rings. The benzofuran dioxetanes <jats:bold>2</jats:bold> were strongly mutagenic in the Salmonella typhimurium strain TA 100, their mutagenicity depending on the type of substituents of the dioxetane and of the benzo rings.</jats:p>