Pyridazines. Part IV. Action of Grignard reagents on 6-methyl- and 4,5-dihydro-6-α-styryl-pyridazin-3(2H)-ones

Abstract

6-Methylpyridazin-3(2H)-one reacts with phenyl- and p-methoxyphenyl-magnesium bromide (4 mol. equiv.) in 1 :1 ether-tetrahydrofuran to give a mixture of the corresponding 4- and 5-aryl-4,5-dihydro-6-methylpyridazin-3(2H)-ones. With p-tolyl- and α-naphthyl-magnesium bromide, only the corresponding 4-aryl-4,5-dihydro-pyridazin-3(2H)-ones are obtained. When the reaction is carried out in tetrahydrofuran, 4-aryl-6-methylpyridazin-3(2H)-ones are obtained.

4,5-Dihydro-6-α-styrylpyridazin-3(2H)-one reacts with p-anisyl-,p-tolyl-, and α-naphthyl-magnesium bromide (3 or 4 mol. equiv.) in tetrahydrofuran or ether-tetrahydrofuran to give 3-aryl-4,5-dihydro-6-α-styrylpyridazines and/or 3-aryl-6-α-styrylpyridazines. Use of phenylmagnesium bromide, however, gives 3,4-diphenyl-6-α-styrylpyridazine.