[N:1]([CH2:4][C@@H:5]1[C@@H:9](O)[CH2:8][N:7]([C:11]([O:13][CH2:14][C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)=[O:12])[CH2:6]1)=[N+:2]=[N-:3].C(N(S(F)(F)[F:27])CC)C.C(=O)(O)[O-].[Na+]>ClCCl>[N:1]([CH2:4][C@@H:5]1[C@H:9]([F:27])[CH2:8][N:7]([C:11]([O:13][CH2:14][C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)=[O:12])[CH2:6]1)=[N+:2]=[N-:3]Process A: (3R,4R)-3-Azidomethyl-1-benzyloxycarbonyl-4-hydroxypyrrolidine (1.20 g) was dissolved in dichloromethane (40 mL). While this solution was chilled in a salt/ice bath, diethylaminosulfur trifluoride (1.20 mL) was added dropwise and the mixture was stirred at room temperature for 3 hours. The reaction vessel was again chilled in a salt/ice bath, followed by dropwise addition of a second portion of diethylaminosulfur trifluoride (0.57 mL) and stirring at room temperature for 2 hours. While the reaction mixture was kept chilled in the ice bath, a saturated aqueous solution of sodium bicarbonate (40 mL) was added dropwise and the dichloromethane layer was separated. The dichloromethane layer was then washed with a saturated aqueous solution of sodium bicarbonate (2×20 mL) and then water (20 mL), dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluant: hexane: ethyl acetate=2:1) to give (3R,4S)-3-azidomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine as a pale brown oil (726 mg).
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