1,2,4‐Thiadiazole 4‐Oxides.

The first N-oxides of the 1,2,4-thiadiazole ring system are prepared by condensation of benzamidoximes with 4,5-dichloro-1,2,3-dithiazolium chloride 1; they are shown by 15N-labelling to be 4-oxides and a mechanism is proposed for their formation.