A convenient synthesis of 1,3-dimethyl(5h,7h)imidazo(4,5-dpyrimidine-2,4,6-trithione and its unusual character

1,3-Diemthyl(5H,7H)imidazo(4,5-$\text{d}$pyrimidine-2,4,6-trithione ($\text{1}$) was synthesized by the reaction of carbon disulfide with 1,3-dimethyl-4-cyano-5-aminoimidazolidine-2-thione ($\text{3}$) which was produced by reacting trimethylsilyl cyanide with methyl isothiocyanate followed by methanolysis. An unusual reversible formation of the dimethylamine salt of $\text{1}$ is also described.