[C:1]([O:5][C:6](=[O:13])[NH:7][C@H:8]1[CH2:11][C@@H:10]([OH:12])[CH2:9]1)([CH3:4])([CH3:3])[CH3:2].[H-].[Na+].[CH2:16](Br)[C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1>C1COCC1>[C:1]([O:5][C:6](=[O:13])[NH:7][C@H:8]1[CH2:11][C@@H:10]([O:12][CH2:16][C:17]2[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=2)[CH2:9]1)([CH3:4])([CH3:2])[CH3:3]tert-Butyl(cis-3-hydroxycyclobutyl)carbamate (2.0 g, 10.7 mmol) was dissolved in dry THF (50 mL) under nitrogen atmosphere, and the solution cooled to 0° C. To this clear solution, sodium hydride (60% dispersion in oil, 0.428 g, 10.7 mmol) was added portion wise (evolution of H2 observed). The mixture was stirred at rt for 30 min then benzyl bromide (1.91 mL, 16.04 mmol) added dropwise and the resulting yellow suspension stirred at rt for 16 h. The reaction was quenched with sat aq. NH4Cl solution (20 mL) and partitioned between sat aq. NaHCO3 (40 mL) and DCM (60 mL). The combined organic fractions were washed with brine (20 mL), dried (MgSO4) and concentrated in vacuo. The resulting residue was purified by column chromatography (gradient 0-50% EtOAc in cyclohexane) to afford the title compound as a white solid (2.40 g, 81%). 1H NMR (CDCl3, 400 MHz): δ 7.41-7.22 (5H, m), 4.66 (1H, br, NH), 4.42 (2H, s), 3.83-3.65 (2H, m), 2.79-2.61 (2H, m), 1.86-1.72 (2H, m), 1.46 (9H, s).
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