Formation of substituted 1-Benzazepine-2,5-diones from derivatives of kynurenine

Several N-protected DL-kynurenine derivatives have been converted into 3-substituted 3,4-dihydro-1H-1-benzazepine-2,5-diones by thermal cyclization. This reaction was found to proceed less readily than the analogous formation of 1,4-benzodiazepine-2,5-diones from o- aminobenzoylamino acids. The incidence of specific peptide bond cleavage involving these cyclizations was investigated with model compounds.