Phthalazines. III. : On the Reaction of 1-(Methylsulfonyl)-4-phenylphthalazine with Ketones

Abstract

The ring-carbon in of 1-position 1-(methylsulfonyl)-4-phenylphthalazine (I) is active to nucleophilic reagents and the methylsulfonyl group is substituted. In order to examine the action of carbanion as the nucleophilic reagent, reaction of I with various ketones, in the presenceof sodium amide (A method) or sodium hydroxide (B method), was carried out. The ketones used were acetophenone (IIa), propiopthenone (IIb), diethyl ketone (IId), acetone (IIc), methyl ethyl ketone (IIe), methyl propyl ketone (IIf), methyl isobutyl ketone (IIg), methyl isopropyl ketone (IIh), cyclopentanone (IIi), cyclohexanone (IIj), and l-p-menthan-3-one (IIk), Results of these reactions and products thereby obtained are listed in Tables I, II, and III. When the methyl group adjacent to the carbonyl group has reacted and when the methylene group reacted proved to show a marked difference in the products with respect to the color reaction with ferric chloride, and in their infrared and ultraviolet spectra (Tables II and III). This difference is assumed to arise from the fact that the compounds obtained by the reaction with the methyl group adjacent to the carbonyl exist in tautomeric form, as shown in the Chart, (p. 809) while such a tautomerism does not exist in the other compounds.