13C NMR spectra of benzodiazepinones: Application to isomeric structure determination

A 13C NMR study of a number of substituted 1,5-benzodiazepin-2-ones has been carried out, and shows that this technique is one of the rare spectroscopic methods which allows an unambiguous identification of the number and nature of the isomers formed in the condensation of a β-ketoester with a substituted O-phenylenediamine.