2-Oxo-3-tert-butoxycarbonylamino-5-pivaloyl-8-methyl-1,3,4,5-tetrahydro-2H-1,5-benzodiazepine (1.0 g) obtained from Step 1 of Example 89 was dissolved in tetrahydrofuran (10 ml), 60% sodium hydride (0.16 g) was added under argon atmosphere, the mixture was stirred for 30 minutes at room temperature. A solution of 3-bromoacetylthiophene (0.90 g) in tetrahydrofuran (5 ml) was added,stirred for one hour. The reaction mixture was poured into ice-water, extracted with ethyl acetate, the organic layer was successively washed with water and saturated brine, and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, the residue was purified by silica gel column chromatography(n-hexane:ethyl acetate=2:1), to thereby obtain 0.94 g of the titled compound (Yield: 71%).
