Synthesis of sulfanyl-, sulfinyl-, and sulfonyl-substituted bicyclic dioxetanes and their base-induced chemiluminescence.

The singlet oxygenation of 4-tert-butyl-3,3-dimethyl-5-(3-oxyphenyl)-2,3-dihydrothiophenes 5c-e bearing an acetoxy or methoxy group at the 2-position exclusively gave the corresponding sulfanyl-substituted bicyclic dioxetanes 2c-e, while that of 5a without 2-substituent mainly gave sulfoxide 11 along with a small amount of dioxetane 2a. These dioxetanes were sufficiently stable thermally to permit handling at room temperature. Sulfanyl-substituted dioxetanes, 2c and 2e, were further oxidized with m-chloroperbenzoic acid to afford the corresponding sulfinyl-substituted dioxetanes 3c, 3e and sulfonyl-substituted dioxetanes 4c, 4e.