[C:1]([O:5][C:6]([N:8]1[CH2:12][CH2:11][C:10](=[O:13])[CH2:9]1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[C:14]([Mg]Br)#[CH:15]>O1CCCC1>[C:1]([O:5][C:6]([N:8]1[CH2:12][CH2:11][C:10]([C:14]#[CH:15])([OH:13])[CH2:9]1)=[O:7])([CH3:4])([CH3:2])[CH3:3]This compound was prepared according to a procedure similar to that described in Procedure A. In a solution of 3-Oxo-pyrrolidine-1-carboxylic acid tert-butyl ester (3.0 g, 16.2 mmol) in tetrahydrofuran (40 mL) was dropped in ethynyl magnesium bromide (70 mL, 35 mmol) at −78° C. Then the solution was stirred overnight at room temperature. Then the reaction mixture was quenched with saturated NH4Cl and extracted with dichloromethane, dried with anhydrous sodium sulfate to afford 3-Ethynyl-3-hydroxy-pyrrolidine-1-carboxylic acid tert-butyl ester (1.5 g, 44%).
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