[NH2:1][C:2]([C@@H:4]1[CH2:8][C@@H:7]([OH:9])[CH2:6][N:5]1[C:10]([O:12][C:13]([CH3:16])([CH3:15])[CH3:14])=[O:11])=O.FC(F)(F)C(OC(=O)C(F)(F)F)=O.O.C(OCC)(=O)C>N1C=CC=CC=1>[C:13]([O:12][C:10]([N:5]1[CH2:6][C@H:7]([OH:9])[CH2:8][C@H:4]1[C:2]#[N:1])=[O:11])([CH3:16])([CH3:14])[CH3:15]7.82 g (34 mmol) of tert-butyl (2S,4R)-2-(aminocarbonyl)-4-hydroxypyrrolidine-1-carboxylate was dissolved in 80 ml of pyridine and 12 ml (84 mmol) of trifluoroacetic anhydride was added to the solution dropwise, at −20 C□. The mixture was stirred at room temperature for a day. The excess of anhydride was hydrolised by addition of some drops of water. To this mixture 200 ml of ethyl acetate was added and it was washed with 10% aqueous hydrogen chloride (to pH 3-5), 50 ml 2 N solution of sodium hydroxide and 50 ml brine. The organic solution was dried over sodium sulphate and evaporated to result in an oil. Yield: 5.35 g (74%). (MH30)=213, (MH+)2=426.
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