[C:1]1([CH2:7][O:8][C:9]([N:11]2[CH2:15][CH2:14][CH:13]([C:16]([OH:18])=[O:17])[NH:12]2)=[O:10])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.CCN(C(C)C)C(C)C.[CH:28]([N:30]([CH2:39][C@@H:40]([CH2:44][CH2:45][CH2:46][CH2:47][CH3:48])[C:41](F)=[O:42])[O:31][CH2:32][C:33]1[CH:38]=[CH:37][CH:36]=[CH:35][CH:34]=1)=[O:29].CC(O)=O>CN(C=O)C>[CH:28]([N:30]([CH2:39][C@@H:40]([CH2:44][CH2:45][CH2:46][CH2:47][CH3:48])[C:41]([N:12]1[C@H:13]([C:16]([OH:18])=[O:17])[CH2:14][CH2:15][N:11]1[C:9]([O:8][CH2:7][C:1]1[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1)=[O:10])=[O:42])[O:31][CH2:32][C:33]1[CH:34]=[CH:35][CH:36]=[CH:37][CH:38]=1)=[O:29]To a 50 mL round-bottomed flask was added 1-{[(phenylmethyl)oxy]carbonyl}-3-pyrazolidinecarboxylic acid (3.00 g, 8.23 mmol) and Hunig's base (DIPEA) (4.41 mL, 25.3 mmol) in DMF (15 mL). To this mixture was added (2R)-2-({formyl[(phenylmethyl)oxy]amino}methyl)heptanoyl fluoride (1.87 g, 6.33 mmol) in DMF (5 mL) dropwise. The reaction mixture was stirred at room temperature overnight, then was stored in refrigerator for two days. HOAc (3 ml) was added to neutralize the excess Hunig's base. The resulting solution was purified by RP-HPLC to provide (3S)-2-[(2R)-2-({formyl[(phenylmethyl)oxy]amino}methyl)heptanoyl]-1-{[(phenylmethyl)oxy]carbonyl}-3-pyrazolidinecarboxylic acid as a white solid (1.153 g, 35%). LCMS: (M+H)+: 526.0.
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