A solution of 250 mg (1.12 mmol) (S)-7-amino-5H,7H-dibenzo[b,d]azepin-6-one and 256 mg (1.12 mmol) (RS)-2-hydroxy-2-(2,2,2-trifluoro-ethylcarbamoyl)-butyric acid in 24 ml tetrahydrofuran were cooled to 0° C. and 174 mg (0.94 mmol) 1-hydroxy-benzotriazole hydrate, 390 μl (2.23 mmol) diisopropylethylamine and 218 mg (1.12 mmol) N-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide hydrochloride were added. Stirring was continued overnight at room temperature. Removal of the solvent by distillation and chromatography on silicagel with ethylacetate/heptane 2/8 yielded 330 mg (68%) (R/S)-2-ethyl-2-hydroxy-N-((S)-6-oxo-6,7-dihydro-5H-dibenzo[b,d]azepin-7-yl)-N′-(2,2,2-trifluoro-ethyl)-malonamide as a colorless oil, MS (m/e): 436.1 (M+H)+.
