Ring-chain isomerism of 3-hydroxy-3-(2-imidazolyl)isoindolinones

Abstract

It was established by IR, UV, and PMR spectroscopy that N-unsubstituted and N-(n-alkyl, sec-alkyl, or aryl)-2-(2-imidazolylcarbonyl)benzamides obtained from imidazo[1,2-b]isoquinoline-5,10-dione and ammonia or amines have the 3-hydroxy-3-(2-imidazolyl)isoindolinone chain structure in the crystalline state and in solutions in dimethyl sulfoxide. The N-(tert-alkyl)amides exist in the open form under these conditions. Protonation of the imidazole nitrogen atom in the N-(tert-butyl)amide molecule leads to its cyclization to 3-hydroxyisoindolinone.