ピリダジン誘導体の合成 (第4報)

Abstract

Nitration of pyridazine 1-oxide (I), 3-methylpyridazine 2-oxide (II), 3, 6-dimethyl-pyridazine 1-oxide (III), 3-methoxy-6-methylpyridazine 1-oxide (IV), and 3-chloro-6-methylpyridazine 1-oxide (V) afforded nitrated derivatives, which were all assumed to be 4-nitro compound, and it was confirmed that the same position is nitrated with respect to the N-oxide group in (II), (III), (IV), and (V). The nitro group in these compounds substituted with methoxyl by treatment with sodium methoxide. The nitro group alone is reduced by catalytic reduction over palladium-carbon but both the nitro and N-oxide group are reduced by catalytic reduction over Raney nickel, forming aminopyridazines. Effect of a substituent present is marked in nitration and nitration progreses smoothly when an electron-releasing group is present in the ring.