Condensation of o-aminophenol and α-dicarbonyl compounds. Part 2. Dibenzoxazolines

The study of 2′-aryl-2,2′-dibenzoxazolines (II), obtained together with 2-hydroxy-(2H)-1,4-benzoxazines (1) by condensation of o-aminophenol with a series of phenylglyoxal derivatives, emphasized that these compounds are an equilibrium mixture of dibenzoxazolines and related tautomeric ketimine forms. This behaviour was widely investigated by ir, uv and pmr spectroscopy. J. Heterocyclic Chem., 14, 957 (1977)