Pyridazine Derivatives. VIII. : Transetherification in Alkoxypyridazine N-Oxides.

Abstract

Ether-exchange reactions using sodium methoxide or ethoxide were examined with 3-methoxy-(IXa), 3-methoxy-4-methyl-(IXb), 3-methoxy-6-chloro-(Va), 3-methoxy-4-methyl-6-chloro-(Vb), 3-ethoxy-6-chloro-(VIa), 3, 6-dimethoxy- (Ia), 3, 6-diethoxy- (IIa), and 3, 6-diethoxy-4-methylpyridazine 1-oxide (IIb), and 4-methoxy (XIIa) and 4-ethoxypyridine 1-oxide (XIIb). Ether exchange takes place under mild conditions and, dialkoxy compounds undergo hydrolysis under drastic conditions, forming hydroxy compounds (VII or VIII). In dimethoxy compounds, 3-position is more active than the 6-position, while this is reversed in diethoxy compounds. In dialkoxy compounds, methoxyl group is more sensitive to the ether exchange reaction than the ethoxyl group. 3-Alkoxy- and 3, 6-dialkoxy-pyridazine 1-oxides submit more easily to the ether exchange reaction than 3, 6-dialkoxypyridazine or 4-alkoxypyridine 1-oxide.