Reaction Steps
(3(S)-tert-Butoxycarbonylamino-2-oxo-2,3,4,5-tetrahydrobenzo[b][1,4]diazepin-1-yl)acetic acid methyl ester (103). A 1.0 M solution of lithium bis(trimethylsilyl)amide (3.4 ml, 3.4 mmol) in THF was added dropwise to a -78° C. solution of 3-tert-butoxycarbonylamino-1,3,4,5-tetrahydrobenzo[b][1,4]diazepin-2-one (0.94 g, 3.38 mmol) in 20 ml of anhydrous tetrahydrofuran and stirred for 30 minutes. Methyl bromoacetate (o.44 ml, 4 mmol) was added dropwise to the reaction mixture then warmed to room temperature. The reaction was diluted with 100 ml of ethyl acetate and washed with 0.3N potassium hydrogen sulfate (50 ml), water (2×50 ml), and brine. The combined organics were dried over anhydrous sodium sulfate, filtered, and evaporated to afford a gum that was purified by flash chromatography eluting with 3:7 EtOAc/Hex. to give 0.98 g (83%) of the title compound as a white solid. 1H NMR (CDCl3) δ 7.15-7.07 (2H, m), 6.98-6.94 (1H, m), 6.88-6.84 (1H, d), 5.62-5.55 (1H, d), 4.71-4.65 (1H, d), 4.65-4.6 (1H, m), 4.33-4.27 (1H, d), 3.96-3.90 (1H, m), 3.78 (3H, s), 3.44-3.37 (1H, m), 1.4 (9H, s). ##STR163## [2-Oxo-3(S)-(3-phenylpropionylamino)-2,3,4,5-tetrahydro-benzo[b] [1,4]diazepin-1-yl]acetic acid methyl ester (104a). Anhydrous hydrogen chloride was bubbled into a solution of (3(S)-tert-butoxycarbonylamino-2-oxo-2,3,4,5-tetrahydro-benzo[b] [1,4]diazepin-1-yl)acetic acid methyl ester (103, 1 g, 2.86 mmol) in 25 ml of ethyl acetate for 2 minutes then stirred for 1 hour at room temperature. The reaction was evaporated to give 2-oxo-3(S)-amino-2,3,4,5-tetrahydrobenzo[b][1,4]diazepin-1-yl acetic acid methyl ester hydrochloride as a white solid. The hydrochloride salt and hydrocinnamic acid (0.47 g, 3.15 mmol) was dissolved into 20 ml of dimethylformamide and cooled to 0° C. Diisopropylethylamine (1 ml, 5.72 mmol) was added to the solution followed by the addition of N-hydroxybenzotriazole and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride. After stirring for 18 hours at room temperature, the mixture was diluted with 150 ml of ethyl acetate and washed with 10% sodium hydrogen sulfate, 10% sodium bicarbonate, and brine. The organic layer was dried over anhydrous sodium sulfate, filtered, and evaporated to a crude solid that was purified by flash chromatography eluting with 7:3 ethyl acetate/dichloromethane to afford 600 mg (55%)of the title compound as a white solid. 1H NMR (CDCl3) δ 7.3-6.85 (9H,m), 6.55-6.0 (1H, d), 4.88-4.82 (1H, m), 4.72-4.65 (1H, d), 4.28-4.22 (1H, m), 3.95-3.9 (1H, m), 3.78 (3H, s), 3.65 (1H, br. s), 3.28-3.2 (1H, m), 2.95-2.84 (2H, m), 2.55-2.4 (2H, m).
