Process (B): (3R,4R)-3-Azidomethyl-1-benzyloxycarbonyl-4-hydroxypyrrolidine (1.79 g) was dissolved in toluene (56 mL). While this solution was cooled on an ice bath, 1,8-diazabicyclo[5.4.0]undec-7-ene (2.03 mL) was added. This was followed by dropwise addition of perfluoro-1-octanesulfonyl fluoride (2.80 mL) and stirring for another 1 hour. Insoluble materials were removed from the reaction mixture by filtration and were washed with toluene. The filtrate and the washing solution were combined and the combined organic layer was concentrated under reduced pressure. The resulting residue was then purified on a silica gel column (eluant=hexane:ethyl acetate=2:1) to give 1.58 g of (3R,4S)-3-azidomethyl-1-benzyloxycarbonyl-4-fluoropyrrolidine as a pale brown syrup-like product. The compound was identical to the compound obtained by Process (A).
