Oxidation of Dithia Compounds: Comparative Experimental and Theoretical Studies on 1,3‐Bis(methylthio)propane, Bis(methylthio)methane, and meso‐4,6‐Dimethyl‐1,3‐dithiane

Abstract

1,3‐Bis(methylthio)propane, bis(methylthio)methane, and meso‐4,6‐dimethyl‐1,3‐dithiane were oxidized with 1–4 equivalents of hydrogen peroxide, meta‐chloroperbenzoic acid, sodium periodate, or potassium permanganate, respectively, and the amounts of oxidized substrates (sulfoxides and/or sulfones) were determined by NMR spectroscopy. Sulfanyl groups in the former starting material turned out to behave like independent functions, while a mutual influence of the sulfur functions was verified in the latter compounds. A meaningful investigation was possible in the conformationally constrained dithiane derivative. Oxidation of the dithiane with stoichiometric amounts of periodate led to exclusive formation of bissulfoxides, while hydrogen peroxide and meta‐chloroperbenzoic acid yielded the possible products less specifically and permanganate preferentially furnished sulfones. The experimental investigations were supported by calculations on energies and stereoelectronic effects of starting materials, products, and transition states. The unique property of permanganate to exclusively yield sulfones might be due to its special oxidation mechanism, where the sulfur is not only acting as nucleophile, but concomitantly as electrophilic moiety.