[C:1]([N:8]1[CH2:15][CH2:14][CH2:13][C@@H:9]1[C:10]([OH:12])=O)([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].CN1CCOCC1.ClC(OCC(C)C)=O.[Br:31][C:32]1[CH:38]=[CH:37][CH:36]=[CH:35][C:33]=1[NH2:34]>ClCCl>[Br:31][C:32]1[CH:38]=[CH:37][CH:36]=[CH:35][C:33]=1[NH:34][C:10]([C@H:9]1[CH2:13][CH2:14][CH2:15][N:8]1[C:1]([O:3][C:4]([CH3:5])([CH3:6])[CH3:7])=[O:2])=[O:12]In a 500 mL flask, N-Boc-D-Proline (300 mg, 1.39 mmol) was dissolved in dichloromethane (35 mL) and cooled to 0° C. under nitrogen. N-Methylmorpholine (153 μL, 1.39 mmol) was added followed by dropwise addition of iso-butyl chloroformate (180 μL, 1.39 mmol) and the reaction mixture stirred at 0° C. for 1 h. 2-Bromoaniline (1.31 mL, 1.39 mmol) was dissolved in dichloromethane (5 mL) then added quickly to the activated acid at 0° C. The mixture was stirred overnight from 0° C. to room temperature. The reaction mixture was diluted with dichloromethane, washed with water, dried over Na2SO4 and concentrated under reduced pressure. The crude mixture was purified on column chromatography (eluent: Pentane/EtOAc, 50/50 to 0/100 then EtOAc/MeOH 80/20) to give the product (394 mg, 77%) as a yellow oil. This product was used in the next step without further purification.
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