The reactions of methyl (or ethyl) isothiocyanate with dianions (4, 5, and 6), which are readily derived from available cyclicthioureas (1, 2, and 3) with butyllithium, gave ring fused 1,3-disubstituted 1,3,5-triazine-2,4(1H,3H)-dithiones (7) and/or thiocarbamoyl derivative (8) as major products.
5,6-Dihydro- 1,3,5-trimethyl-6-methylimino-1,3,5-triazine-2,4-(1H,3H)-dithione (1) was synthesized by the reaction of methyl isothiocyanate underhighpressure in the presence of Et3N and H2O. The yield and selectivity of 1 were seriously effected by pressure, reaction temperature, solvent, and the amount of H2O.