PREPARATION OF 3-HYDROXYISOINDOLIN-1-ONES AND O-ACYLBENZAMIDES - A STUDY OF RING-CHAIN TAUTOMERISM

3-Hydroxyisoindolinones (ring form) as well as their chain tautomers, o-acylbenzamides, were prepared from the reactions of 3-benzalphthalide 1, 3-halophthalides 3, and o-acylbenzoic acids 6 or their esters 7 with amines 2, and those of phthalimides 4 with Grignard reagents 5. The characteristic spectroscopic properties of ring and chain forms are observed in the ir and C-13-nmr spectra. The significance of the spectroscopic results is discussed, as is the relationship between the structure of the products and the position of the ring-chain equilibrium.