Abstract
Eleven 6-methyl- and 6-phenyl-thiazolo [3, 2-b] pyridazin-4-ium perchlorates (I) are synthesized by acid-cyclization of the corresponding ketosulfides (VI) and thioacetonitriles (VII) which are prepared from 6-methyl-and 6-phenyl-pyridazine-3 (2H) thiones (IVa, b) by alkylation with α-haloketones (V) and α-chloroacetonitrile, respectively. Treatment of the quarternary salts (I) with potassium hydroxide or secondary amines furnishes 2-(2-mercaptovinyl) pyridazine-3 (2H)-ones (XII), nucleophilic attack of the hydroxide ion taking place at the C8a-position of the thiazolo [3, 2-b] pyridazinium system.
