[C:1]([O:5][C:6]([N:8]1[CH2:12][CH2:11][CH2:10][C@H:9]1[C:13]#[N:14])=[O:7])([CH3:4])([CH3:3])[CH3:2].[N-:15]=[N+:16]=[N-:17].[Na+].[Cl-].[NH4+].C(O)(=O)CC(CC(O)=O)(C(O)=O)O>CN(C)C=O>[C:1]([O:5][C:6]([N:8]1[CH2:12][CH2:11][CH2:10][C@H:9]1[C:13]1[NH:17][N:16]=[N:15][N:14]=1)=[O:7])([CH3:4])([CH3:2])[CH3:3]To a solution of (S)-2-Cyano-pyrrolidine-1-carboxylic acid tert-butyl ester (500 mg, 2.55 mmol) in N,N-dimethyl-formamide (20 mL) is added sodium azide (174 mg, 2.68 mmol) and ammonium chloride (150 mg, 2.81 mmol). The solution is stirred at 93° C. over night. The solution is poured into 5% citric acid solution with ice, and the mixture is extracted with EtOAc. The organic extract is washed with brine, dried and concentrated under vacuum. The crude oil is used directly in the next step without further purification. M+H+=240.
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