Synthesis of Novel Fused Heterocyclic Compounds from 7-amino-{[}1,2,4]triazino{[}3,4-b]{[}1,3,4]thiadiazine-8-carbonitrile

A one-pot synthesis of 7-amino-4-oxo-3-(2-(2-thienyl)vinyl)-4,8-dihydro-{[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazine-8-carbonitrile (2) via the reaction of 4-amino-3-sulfanyl-6-{[}2-(2-thienyl)vinyl]-1,2,4-triazin-5(4H)-one (1) with bromomalononitrile is described. The formation of the new fused heterobicyclic and heterotricyclic nitrogen systems ({[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazin-7-yl) guanidine 3, pyrimido{[}4,5-e]{[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazin-4-one 5, {[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazin-7-ylcarbamodithioic acid 6, pyrimido{[}4,5-e]{[}1,2,4] triazino{[}3,4-b]{[}1,3,4] thiadiazin-4-one 8, {[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazin-7-ylformimidate 9, pyrido{[}2,3-e]{[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazine-9-carbonitrile 11, (pyrimido{[}4,5-e]{[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazin-8-yl) acetonitrile 12 and pyrimido{[}4,5-e]{[}1,2,4] triazino{[}3,4-b]{[}1,3,4]thiadiazine-4,10(10aH)-dione 13 was achieved by treating 2 with cyanamide, urea, thiourea, CS2 and ethanolic ethoxide, formamide, triethyl orthoformate, malononitrile, ethyl cyanoacetate and chloroacetyl chloride, respectively. Additionally, the 8-thiourea and 8-acetamide derivatives 16a,b, 18 and 19 were synthesized by reacting 2 with various isothiocyanate derivatives and acetic anhydride. The structures of all synthesized compounds were deduced by elemental analysis, mass spectrometry and analysis of their spectral data (IR, H-1 NMR, C-13 NMR).