[C:1]([O:5][C:6](=[O:14])[NH:7][CH:8]1[CH2:13][CH2:12][NH:11][CH2:10][CH2:9]1)([CH3:4])([CH3:3])[CH3:2].[O:15]1[CH2:18][CH2:17][C:16]1=O.C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+]>ClCCCl>[C:1]([O:5][C:6](=[O:14])[NH:7][CH:8]1[CH2:13][CH2:12][N:11]([CH:17]2[CH2:18][O:15][CH2:16]2)[CH2:10][CH2:9]1)([CH3:4])([CH3:2])[CH3:3]To a suspension of piperidin-4-yl-carbamic acid tert-butyl ester (200 mg, 1.0 mmol) in DCE (6 mL) was added oxetanone (60 mg, 0.83 mmol) in DCE (2 mL). After 75 min, sodium triacetoxyborohydride (282 mg, 1.33 mmol) was added in one portion. After 20 hours at ambient temperature, the reaction mixture was loaded directly onto a 5 g SCX-2 cartridge which was washed with methanol, then 2N ammonia in methanol. Concentration of the combined basic fractions in-vacuo followed by flash chromatography of the resultant residue (silica, 5 g column, Si-SPE, 0-10% methanol in dichloromethane) afforded the title compound as a white solid (141 mg, 67%). 1H NMR (300 MHz, CDCl3): 4.62-4.61 (m, 4H), 4.44 (s, 1H), 3.46-3.45 (m, 2H), 2.67 (d, J=10.9 Hz, 2H), 2.02-1.88 (m, 4H), 1.44 (s, 9H).
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