[NH2:1][C@H:2]([C:7]1[CH:12]=[CH:11][CH:10]=[C:9]([N+:13]([O-:15])=[O:14])[CH:8]=1)[CH2:3][C:4]([OH:6])=[O:5].S(Cl)([Cl:18])=O.[CH2:20](O)[CH3:21].Cl>O1CCOCC1>[ClH:18].[NH2:1][C@H:2]([C:7]1[CH:12]=[CH:11][CH:10]=[C:9]([N+:13]([O-:15])=[O:14])[CH:8]=1)[CH2:3][C:4]([O:6][CH2:20][CH3:21])=[O:5](S)-3-Amino-3-(3-nitrophenyl)propanoic acid (500 mg, 2.4 mmol) was dissolved in 2.0HCl in dioxane (2 mL) and concentrated in vacuo. In a separate flask thionyl chloride (0.21 mL, 2.8 mmol) was added to ethanol at −10° C. The ethanolic solution was stirred for 20 min at −10° C. then added to the HCl salt of (S)-3-amino-3-(3-nitrophenyl)propanoic acid. The resulting solution was stirred at ambient temperature for 1 h and at 40° C. for 3 h. The reaction mixture was concentrated in vacuo to yield 34A (600 mg, 92%) as a white solid. MS (ESI) m/z 239.09 (M+H)+.
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