NaH (6.1 mg of a 60 wt % dispersion in mineral oil, 0.153 mmol, 1 equivalent) was added to a stirred, room temperature mixture tert-butyl (2R,5S)-2-[(R)-{[tert-butyl(dimethyl)silyl]oxy}(phenyl)methyl]-5-[4-(methylcarbamoyl)benzyl]pyrrolidine-1-carboxylate (80 mg, 0.148 mmol) in DMF (0.74 mL), and the mixture was stirred for 10 minutes. 1-(Bromomethyl)-2-fluorobenzene (0.0281 mg, 0.148 mmol, 1 equivalent) was added and the mixture was stirred overnight. Water was then added and the mixture was partitioned with EtOAc. The aqueous layer was extracted with EtOAc (3×), and the combined organic extracts were washed with brine, dried with Na2SO4, filtered, and concentrated in vacuo. The residue was purified by normal phase flash chromatography using silica gel (0-50% hexanes/ethyl acetate). The product was collected and concentrated in vacuo to afford the title compound (95 mg, 99%). LC-MS=669.2 (M+Na)+.
