Abstract
Acid-catalyzed condensation of 2-amino-3-mercapto-6-methylpyridine and 3-amino-pyridine-2 [1H]-thiones with 4-chloropyrimidines having free 5-carbon centers gave N-(3-mercapto-2-pyridyl)-6-pyrimidinylamines and N-(2-thioxo-3-pyridyl)-6-pyrimidinyl-amines, which we have described as open 1, 3, 9-triaza- and 1, 3, 6-triaza-phenothiazines, respectively. A newly developed method of reducing nitro groups was used for preparing the aminopyridine precursors. Eight new and five related compounds including an open 1, 9-diazaphenoxazine were tested in rats and mice and found to display central nervous system (CNS)-depressant activities. The most active compound in the series is N-(6-chloro-2 [1H]-thioxo-3-pyridyl)-2, 4-diamino-6-pyrimidinylamine, an open 1, 3, 6-triaza-phenothiazine derivative. Structure-activity correlations are discussed on the basis of the biological data.
