treatment of 1-(5-bromo-2-chloro-6-methylpyrimidin-4-yl)-1-methylhydrazine withdimethylthiocarbamoylchloride gave 7-chloro-n,n, 1,5-tetramethyl-1h-pyrimido[4,5-e][1,3,4]thiadiazin-3-amine in basic acetonitrile. the latter compounds were reacted withsecondary amines in boiling ethanol to afford the related 7-amino derivatives.