[Br:1][C:2]([OH:12])([CH3:11])[CH2:3][CH2:4][CH:5]1[NH:9][C:8](=[O:10])[CH2:7][CH2:6]1.[Si:13](Cl)([C:16]([CH3:19])([CH3:18])[CH3:17])([CH3:15])[CH3:14].N1C=CN=C1>CN(C=O)C.CN(C1C=CN=CC=1)C>[Br:1][C:2]([O:12][Si:13]([C:16]([CH3:19])([CH3:18])[CH3:17])([CH3:15])[CH3:14])([CH3:11])[CH2:3][CH2:4][CH:5]1[NH:9][C:8](=[O:10])[CH2:7][CH2:6]1To a solution of 5-(3-bromo-3-hydroxy-butyl)-pyrrolidin-2-one (6.76 g, 21.6 mmol) in DMF (86 mL) was added tert-butyldimethylsilyl chloride (3.59 g, 23.8 mmol) followed by imidazole (2.95 g, 43.3 mmol) and DMAP (264 mg, 2.16 mmol). The reaction was stirred for 24 h and was quenched with saturated aqueous ammonium chloride. The aqueous solution was washed with EtOAc (3×) and the combined organic extracts were dried (MgSO4), filtered, and concentrated. Purification by medium pressure chromatography using a solvent gradient (CH2Cl2 to 1% MeOH in CH2Cl2 to 3% MeOH in CH2Cl2 to 5% MeOH in CH2Cl2 to 8% MeOH in CH2Cl2) provided 5-[3-bromo-3-(tert-butyl-dimethyl-silanyloxy)-butyl]-pyrrolidin-2-one (7.45 g). 1H NMR (CDCl3) δ7.30 (m, 2H), 7.12 (m, 1H), 7.04 (m, 1H), 5.71 (m, 1H), 3.81 (m, 1), 3.56 (m, 1H), 2.66 (m, 2H), 2.32-2.17 (m, 3H), 1.70-1.35 (m, 5H), 0.82 (s, 9H), −0.06 (d, 3H), −0.24 (d, 3H); MS 426.2, 428.2 (M+).
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