azides, on thermolysis in refluxing toluene, give 3-substituted 1,4,2-dithiazines which thermally extrude sulfur atom of the 4-position selectively to yield 3-substituted isothiazoles, while 2-unsubstituted 1,3-dithiol-2-yl azides undergo both ring expansion yielding 1,4,2-dithiazines and peculiar thermal dissociation into 1,3-dithiol-2-ylidene carbenes and hydrogen azide.