Effective precursors for sulfur monoxide formation

When triphenylmethanesulfenyl chloride (12) (or its thio 13 or dithio homolog 14) are treated with hindered olefins 15 and 16, thiiranes 10 and 11, are produced in high isolated yields (ca. 94%). Treatment of 10 and 11 with m-chloroperoxybenzoic acid (m-CPBA) leads to the formation of thiirane 1-oxides 8 and 9 (99% isolated yields). The structures of 8-11 were established by H-1 and C-13 NMR, mass spectrometry as well as by X-ray. Thermal decomposition of either 8 or 9 smoothly delivers sulfur monoxide to various 1,3-dienes giving cyclic sulfoxides in good yield. A variety of conditions were employed to optimize the yield of the trapped adducts.