[CH3:1][O:2][C:3](=[O:9])[C@H:4]([CH:6]([CH3:8])[CH3:7])[NH2:5].N1C=CC=CC=1.[Br:16][CH2:17][CH2:18][CH2:19][C:20](Cl)=[O:21]>C(Cl)Cl>[CH3:1][O:2][C:3](=[O:9])[C@H:4]([CH:6]([CH3:8])[CH3:7])[NH:5][C:20](=[O:21])[CH2:19][CH2:18][CH2:17][Br:16]To a solution of 1.08 g (8.4 mmole) of L-valine methyl ester in 30 ml of CH2Cl2 was added 1.36 ml (16.8 mmole) of pyridine, cooled to 0° C. and 1.55 g (8.4 mmole) of 4-bromobutanoyl chloride added. The solution was stirred at 0° C. for 40 minutes and at RT for 1 h. The solution was washed with satd. NaHCO3, brine and dried with anrhy. Na2SO4; filtered and concentrated in vacuo. The crude product was purified by silica gel column chromatography (5% EtOAc/CH2Cl2) to provide 1.82 g (77%) of desired product. 300 MHz 1H NMR (CDCl3) δ 0.92 (d, J=6 Hz, 3H), 0.96 (d, J=6 Hz, 3H) 2.20 (m, 3H), 2.46 (m, 2H), 3.50 (m, 2H), 3.76 (s, 3H), 4.58 (dd, J=4.7 Hz, 1H), 5.97 (br d, J=7 Hz, 1H). Mass spectrum: (M+H)+297.
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