In the previous paper we have assumed that 3-amino-4-oxoisocarbostyril (V) would be formed during catalytic hydrogenation of 3-oximino-4-oxoisocarbostyril (III) in the presence of hydrochloric acid, but, after various examinations, the compound (V) was found to be 3-carbamoylphthalimidine (VI) formed by the ring contraction of III. Furthermore, acid hydrolysis of VI afforded an acid (VII), whose IR spectrum (in KBr) was not identical with that of the product obtained by alkaline hydrolysis of VI. In this case the IR (in dioxan) and NMR spectra of VII and hydrolytic product of VI were completely identical. The crystalline form of VII varies according to the solvent of recrystallization. These facts show that the two forms of crystals would be dimorphic.
