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 SO(2) 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.

A three‐membered vic‐disulfoxide, 3,3‐di‐tert‐butyldithiirane trans‐1,2‐dioxide (8), was synthesized by oxidation of the corresponding dithiirane 1‐oxide 15 in high yield. Treatment of 8 and 15 with a platinum(0) complex, [(Ph3P)2Pt(η2‐C2H4)], yielded the (disulfenato)PtII complex 18 and the (sulfenato–thiolato)PtII complex 14, respectively, in high yields. Oxidation of the sulfenato–thiolato complex 14 with an acetone solution of dimethyldioxirane (DMD) took place at the sulfenato sulfur atom to yield the (sulfinato–thiolato)PtII complex 19, while the oxidation with CF3CO3H occurred at the thiolato‐sulfur atom leading to the disulfenato complex 18. Oxidation of 14 with MCPBA formed both 18 and 19. The position of oxidation on 14 with DMD was dependent on the acidity of a coexisting acid. Thus, oxidation of 14 with DMD/CF3CO2H provided 18 and that with DMD/PhCO2H gave 19. Oxidation of 14 with an excess amount of DMD yielded the (disulfonato)PtII complex 20.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)