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The preparation of silyl thioketones, and their reactions leading to silylated thiirans and other hitherto unknown silylated heterocycles, are reported.

(E)-Phenyl and (E)-(p-tolyl) trimethylsilyl thioketone S-oxides can be easily and stereospecifically protodesilylated into the corresponding (Z)-aryl thioaldehyde S-oxides; these stable liquid lachrimatory compounds show good reactivity as heterodienophiles and the reaction with 1,3-dienes is surprisingly non-stereospecific.

Sulphur monoxide, generated in situ from thiiran 1-oxides, reacts with diazomethane derivatives leading to thione S-oxides.

Diarylthioketone S-oxides react with the 2H-azirine (1) in the presence of boron trifluoride–diethyl ether to give the oxathiazines (3)via a 1,3-cyclization across the sulphine C–S–O bond; the oxathiazines (3) rearrange thermally to the sulphoxides (5).