Regioselective geminal dichloride reactivity of 3,4,4,5-tetrachloro-4H-1,2,6-thiadiazine: access to 4,4-dioxo- and dithio-ketals

Treatment of 3,4,4,5-tetrachloro-4H-1,2,6-thiadiazine (2) with selected alkanols, arenols and thiols led to regiospecific substitution of both geminal C-4 chlorines resulting in the formation of ketal or thioketal 3,5-dichloro-4H-1,2,6-thiadiazines 8a–h in 31–97% yields.