[C:1]([O:5][C:6]([N:8]1[CH2:12][CH2:11][C@@H:10]([OH:13])[C@H:9]1[C:14]([OH:16])=[O:15])=[O:7])([CH3:4])([CH3:3])[CH3:2].C([O-])([O-])=O.[Cs+].[Cs+].[CH2:23](Br)[C:24]1[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=1>CO.O>[C:1]([O:5][C:6]([N:8]1[CH2:12][CH2:11][C@@H:10]([OH:13])[C@H:9]1[C:14]([O:16][CH2:23][C:24]1[CH:29]=[CH:28][CH:27]=[CH:26][CH:25]=1)=[O:15])=[O:7])([CH3:4])([CH3:2])[CH3:3]To a solution of (2S,3R)-3-hydroxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester [186132-96-7] (500 mg, 2.162 mmol; Chem-Impex International, Inc.) in MeOH (9.0 mL), cooled to 0° C., was added with stirring a solution of Cs2CO3 (704 mg, 2.162 mmol) in water (6.0 mL). The mixture was concentrated by rotary evaporation and the residue was suspended in DMF (17.0 mL). The suspension was cooled to 0° C., followed by addition of benzylbromide (0.514 mL, 4.32 mmol) and stirring overnight at RT. The reaction mixture was filtered, the filtrate was concentrated under reduced pressure and the residue was dissolved in EtOAc. The organics were washed with aqueous NaHCO3 (2×) and water (2×), dried (Phase separator) and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (EtOAc/c-hexane 2:3) to give the title compound as an oil. MS (LC/MS): 322 [M+H]+, 665 [2M+Na]+; tR (HPLC conditions b): 4.12 min.
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