Deoxygenation of Dithiirane 1-Oxides with Lawesson's Reagent Leading to the Corresponding Dithiiranes

3,3-Disubstituted dithiirane 1-oxides were efficiently reduced with Lawesson's reagent (LR) to give the corresponding dithiiranes. X-ray diffraction analysis of 3,3-di(1-adamantyl)dithiirane is reported. Reaction of ³⁴S-labeled 3,3-di(1-adamantyl)dithiirane 1-oxide with LR produced the corresponding dithiirane in which the ³⁴S atoms were retained quantitatively.