Synthesis of Sulfanyl-, Sulfinyl-, and Sulfonyl-Substituted Bicyclic Dioxetanes and Their Base-Induced Chemiluminescence

The singlet oxygenation of 4-<i>tert</i>-butyl-3,3-dimethyl-5-(3-oxyphenyl)-2,3-dihydrothiophenes <b>5c</b>−<b>e</b> bearing an acetoxy or methoxy group at the 2-position exclusively gave the corresponding sulfanyl-substituted bicyclic dioxetanes <b>2c</b>−<b>e</b>, while that of <b>5a</b> without 2-substituent mainly gave sulfoxide <b>11</b> along with a small amount of dioxetane <b>2a</b>. These dioxetanes were sufficiently stable thermally to permit handling at room temperature. Sulfanyl-substituted dioxetanes, <b>2c</b> and <b>2e</b>, were further oxidized with <i>m</i>-chloroperbenzoic acid to afford the corresponding sulfinyl-substituted dioxetanes <b>3c</b>, <b>3e</b> and sulfonyl-substituted dioxetanes <b>4c</b>, <b>4e</b>. X-ray single crystallographic analysis was performed for <b>2c</b> and <b>4e</b>. Base-induced decomposition of the dioxetanes in DMSO gave light with a maximum wavelength λ<sub>max</sub><sup>CL</sup> at 554 nm for <b>2a</b> and 565 nm for <b>2e</b> in moderate light yields, while sulfinyl-derivative <b>3e</b> gave weak light with λ<sub>max</sub><sup>CL</sup> = 795 nm and sulfonyl-derivative <b>4e</b> gave very weak light with λ<sub>max</sub><sup>CL</sup> = 848 nm.