Synthesis and Reactivity of 3,4-Dimethyl-4H-1,3,4-thiadiazines

3,4-Dimethyl-4H-1,3,4-thiadiazines. novel 8π heterocyclic systems, were prepared by cyclization of α-haloketones with 1,2,4-trialkylthiosemicarbazides. The desulfurization of the products afforded 5-imino-1,2-dimethylpyrazoles by valence isomerization into thia-σ-homopyrazoles.