Cyclic quaternary ammonium salts. Part IV. The synthesis of pyrido[1,2-a]thiazolo[2,3-c]pyrazidi-inium and pyrido[1,2-a]thiazolo-[4,3-c]pyrazidi-inium salts

Abstract

The synthesis of 2-(2-pyridyl)thiazole and the conversion of this base and of 4-methyl-2-(2-pyridyl)thiazole into a variety of substituted pyrido[1,2-a]thiazolo[2,3-c]pyrazidi-inium salts is described. Attempts to convert 4-phenyl-2-(2-pyridyl)thiazole into the corresponding bridged aromatic diquaternary salts were unsuccessful. The synthesis of 2-methyl-4-(2-pyridyl)thiazole and its conversion into several substituted pyrido[1,2-a]thiazolo-[4,3-c]pyrazidi-inium salts is also recorded.