Through cyclization of 4-(dichloromethylene)-5-(aminosulfonylimino)imidazolidin-2-ones by formaldehyde action series of 8-(dichloromethylene)-3,4,7,8-tetrahydro-6H-imidazo[5,1 c][1,2,4,6]-thiatriazin-6-one 2,2-dioxides were synthesized. The PMB-deprotection from the 3rd position of created heterocyclic system and further 3N-alkylation were realized. Their structure parameters were discovered by NMR experiments and X-Ray analysis. The separate products (with allyl, carbethoxymethyl, 2-N-Boc-aminoethyl, 2-(N-Boc-N-isopropoxymethylamino)ethyl substituents in position 3) demonstrated high antiproliferative activity.