Arylhydrazono acetamides 1 react with chloroacetic acid chloride to give N-chloroacetyl derivatives 2. Subsequent reaction with pyridines followed by ring closure yield 1-(4-amino-6-oxopyridazin-5-yl)-pyridinium chlorides 3. Analogously, 1-(6-oxo-pyridazin-5-yl)-pyridinium chloride (5) and 6-oxo-5-pyridinio-pyridazin-4-olate (4) are formed from phenylhydrazono derivatives and pyridine. Treatment of 3 and 4 with hydrazinium hydrate gives 4,5-diamino-6-oxo-pyridazin-3-carbohydrazides 6 and 5-amino-4-hydroxy-pyridazin-6(1H)-one (8). An analogous ring cleavage of 3e and 5 gives rise to 4,5-diamino- and 5-amino-pyridazin-6(1H)-ones 7. On treatment of the pyridinium salts 3 with caustic soda in water, nucleophilic addition of the amino group to the pyridinium ring takes place and stable dehydrated products 9 are isolated.
Belskaia, Natalia P.; Zvereva, Ekaterina E.; Dehaen, Wim, Journal of Chemical Research, Miniprint, 2000, # 12, p. 1367 - 1378
作者:Belskaia, Natalia P.、Zvereva, Ekaterina E.、Dehaen, Wim、Bakulev, Vasiliy A.