To a cooled solution (0° C.) of 2-methyl-malonic acid mono-tert-butyl ester (1.01 g, 5.79 mmol) and 7-amino-5-methyl-5H,7H-dibenzo[b,d]azepin-6-one (1.15 g, 4.83 mmol) in THF (8 ml) was added hydroxybenzotriazole (652 mg, 4.83 mmol), diisopropylethylamine (624 mg, 4.83 mmol)and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (925 mg, 4.83 mmol), and the mixture was stirred overnight at r.t. The solvent was evaporated, the residue was taken up in ethyl acetate, washed with water, and dried (Na2SO4). After evaporation of the solvent, the title compound, MS: m/e=395.3 (M+H+), (920 mg, 48%) was obtained by chromatographic purification of the residue (silica gel, MeOH, CH2Cl2).
