[C:1]([O:5][C:6]([NH:8][C@H:9]([CH2:13][CH2:14][CH3:15])[C:10]([OH:12])=O)=[O:7])([CH3:4])([CH3:3])[CH3:2].CN1CCOCC1.ClC(OCC(C)C)=O.[NH2:31][C:32]1[CH:37]=[CH:36][CH:35]=[CH:34][CH:33]=1>C1COCC1.Cl>[C:1]([O:5][C:6](=[O:7])[NH:8][C@@H:9]([C:10](=[O:12])[NH:31][C:32]1[CH:37]=[CH:36][CH:35]=[CH:34][CH:33]=1)[CH2:13][CH2:14][CH3:15])([CH3:2])([CH3:3])[CH3:4]To a 0° C. solution of the crude carboxylic acid (652 mg, 3.00 mmol) and NMM (0.50 ml, 4.5 mmol) in THF (12 ml) was added isobutyl chloroformate (0.45 ml, 3.5 mmol) and the resulting mixture was stirred at 0° C. for 5 minutes. A solution of aniline (0.45 ml, 4.9 mmol) in THF (3 ml) was then added dropwise. The reaction was warmed to room temperature and stirred for 66 hours. The reaction was diluted with 1M HCl (30 ml) and was extracted with Et2O (25 ml×3). The organic solution was washed with brine (50 ml), was dried (Na2SO4), filtered and concentrated under reduced pressure, giving crude ((R)-1-phenylcarbamoyl-butyl)-carbamic acid tert-butyl ester as an oily, light yellow foam.
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