Synthesis and Properties of a Dithiirane <i>trans</i>-1,2-Dioxide, a Three-Membered <i>vic</i>-Disulfoxide

cis- and trans-3-(1-adamantyl)-3-tert-butyldithiirane 1-oxides were oxidized with dimethyldioxirane to give the trans-1,2-dioxide. Thermal decomposition of the 1,2-dioxide yielded the corresponding (E)- and (Z)-sulfines, thioketone, and cis- and trans-dithiirane 1-oxides. In the thermolysis, decomposition to the sulfines and SO was the main path and that to the thioketone and SO2 was the minor one. The two decomposition processes and epimerization to the cis-1,2-dioxide were analyzed theoretically. SO generated in situ reacted with thioketones as additives to give the corresponding dithiirane 1-oxides.