Dithiocyanogen Reaction without Cleavage of the SS Bond: Cycloaddition with Hexafluoroacetone

Dithiocyanogen 1, a typical pseudohalogen, reacts with hexafluoroacetone 2 in a cycloaddition reaction to give the 4H-dioxazine derivative 3. In this reaction—other than in reactions of 1 leading to thiocyanates–the SS bond is not cleaved; the structure of 3 was determined by X-ray diffraction.