Treatment of sterically crowded thione S-oxides derived from d-camphor with Lawesson’s reagent afforded dithiiranes along with deoxygenation of the starting materials, and the mixtures were subjected to mCPBA oxidation to give the corresponding dithiirane S-oxides and thione S-oxides.

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β-(N,N-Dimethylcarbamoylselenenyl)- and β-(N,N-dimethylcarbamoyltellurenyl)alkenyl ketones were converted into isoselenazoles and isotellurazole Te-oxides, respectively, simply by treating with hydroxylamine-O-sulfonic acid, and deoxygenation of the latter products was successfully carried out by treating with PPh3. Alternative treatment of ynone oxime tosylates with hydrochalcogenide ions or N,N-dimethylchalcogenocarbamate ions also gave the same isochalcogenazole rings. These reactions were assumed to proceed through intramolecular nucleophilic substitution on the nitrogen atom of oxime sulfonates by the attack of in situ generated chalcogen nucleophiles.

3,5-Disubstituted 1,2,4-thiadiazoles 2 were prepared by reaction of thioamides 1 with DMSO in the presence of such an electrophilic reagent as 1-methyl-2-chloropyridinium iodide, benzoyl chloride, acetyl chloride, hydrochloric acid, or trimethylsilyl chloride in organic solvents at room temperature in high yields. Thiadiazoles 2 were also obtained by reaction of 1 with NBS at room temperature in high yields. Thioamide S-oxides reacted with electrophilic reagents at room temperature to give the corresponding thiadiazoles 2 in high yields.

A convenient preparation of 2,4,6-trisubstituted 1,3,5-triselenanes was achieved by the treatment of aldehydes or their acetals with 2,2,4,4,6,6-hexamethyl-1,3,5-triselena-2,4,6-tristannacyclohexane, (Me2SnSe)3, in the presence of BF3·OEt2 and AlCl3.