sulfamoylamidines in 70-80% yields. Sulfamoylamidines undergo condensations with aliphatic and aromaticaldehydes as well as aliphatic ketones to give thiatriazine dioxides in 50-95% yields. The NMR spectroscopic studies reveal ring-chaintautomerism of some thiatriazine dioxides in solution. The ratio between the tautomers depends on the temperature, solvent polarity, and electronic properties of the substituents