Abstract
Two novel fused ring systems made up of 1, 4-thiazine and 3 (2H)-pyridazinone were synthesized. 3, 4-Dihydro-7-methyl-2H-pyridazino [4, 5-b]-1, 4-thiazin-8 (7H)-one was obobtained from the intramolecular cyclization of 4-chloro-5-(2-chloroethylamino)-2-methyl-3 (2H)-pyridazinone with sodium sulfide. An isomer, 3, 4-dihydro-6-methyl-2H-pyridazino-[4, 5-b]-1, 4-thiazin-5 (6H)-one, was directly afforded by the condensation of 4, 5-dichloro-2-methyl-3 (2H)-pyridazinone with sodium 2-aminoethanthiolate.
