反应详情

温度

0 °C

(2R,4S)-5-Biphenyl-4-yl-4-(3-carboxypropionylamino)-2-methylpentanoic acid ethyl ester (3-a, R1=4-oxo-pentanoic acid, R2=H, R3=Et) (5.5 g) is dissolved in toluene (33 ml) at room temperature. Dimethylformamide (0.1 ml) is added. Thionyl chloride (2.4 ml) is then added. The solution is cooled to 0° C. and 2-bromoethanol (0.94 ml) is added. The mixture is stirred at 0° C. for 2 h and then at room temperature for a further 1 h. A further portion of 2-bromoethanol (0.94 ml) is added and the mixture stirred for 0.5 h at room temperature. A further portion of 2-bromoethanol (0.94 ml) is then added and the resulting mixture stirred for 16 h at room temperature. The mixture is concentrated in vacuo to give the crude product. Purification by chromatography Heptane/EtOAc (2:1) gives (2R,4S)-5-Biphenyl-4-yl-4-[3-(2-bromoethoxycarbonyl)propionylamino]-2-methylpentanoic acid (3-a, R1=4-oxo-pentanoic acid 2-bromoethyl ester, R2=H, R3=Et). 1H NMR (DMSO): 1.07 (3H), 1.14 (3H), 1.41 (1H), 1.79 (1H), 2.37 (2H), 2.48 (1H), 2.50 (2H), 2.71 (2H), 3.66 (2H), 3.94 (1H), 3.99 (2H), 4.33 (2H), 7.25 (2H), 7.35 (1H), 7.46 (2H), 7.57 (2H), 7.64 (2H), 7.78 (1H).

1. waitat room temperature for a further 1 h
2. stirringthe mixture stirred for 0.5 h at room temperature
3. stirringthe resulting mixture stirred for 16 h at room temperature
4. concentrationThe mixture is concentrated in vacuo
5. customto give the crude product
6. customPurification by chromatography Heptane/EtOAc (2:1)