3(2H)isoquinolones. 2. Studies on the structure and formation of aminonaphthols obtained in the preparation of 3(2H)isoquinolones

The reaction of a 2‐acylphenylacetic acid derivative (I) with primary amines in glacial acetic acid produces novel, colorless aminonaphthols (III) which are isomeric with the brilliant yellow 3(2H)isoquinolones (II) obtained in the same reaction. A combination of chemical and spectral techniques allowed identification of the isomers as derivatives of 4‐amino‐2‐naphthol. A plausible mechanism of formation of aminonaphthols versus 3(2H)isoquinolones is discussed and supported by chemical synthesis of N‐substituted 2‐aeylphenylacetamides (VIII) and a 1,4‐dihydro‐1‐hydroxy‐3(2H)isoquinolone derivative (IX).