Hydrolysis of the 4-alkyliminothiopyrano2,3-bpyridinedioles (5) and 4-alkylaminothiopyrano2,3-bpyridones (6) resp. with 10 NaOH gives 5,7-dihydroxy-2H-thiopyrano2,3-bpyridine-4(3H)-one (7).7can be obtained in better yield by reaction of 4-dimethylamino-2(1H)-pyridinethione (8) with bistrichlorphenylethylamlonate (2). Aminolysis of7affords the two isomeric products5and6. On treatment with hydrazines,7reacts only to 4-hydrazonoderivatives5. By heating in bromobenzene5dis cyclisized to 1H-5,1,2,6-thiatriaza-acenaphthylen-7-ol (11). On methylation with methyljodide5,6and7furnish the 7-methoxyproducts13,14and12. By heating in 20 NaOH7is transformed into the 2-thioxo-3-pyridylmethylketone16 Aand its tautomer, 2-mercapto-3-pyridylmethylketone16 B. The structures of5,6and7are discussed.
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