To a solution of 5-(3-hydroxy-4-phenyl-butyl)-pyrrolidin-2-one (4.3 g, 18.43 mmol) in DMF (86 mL) was added tert-butyldimethylsilyl chloride (3.06 g, 20.3 mmol) followed by imidazole (2.5 g, 37 mmol) and DMAP (225 mg). The reaction mixture 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. The residue was purified by medium pressure chromatography eluting with a solvent gradient (CH2Cl2 to 1% MeOH in CH2Cl2to 2% MeOH in CH2Cl2) to yield 5.94 g of 5-[3-(tert-butyl-dimethyl-silanyloxy)-4-phenyl-butyl]-pyrrolidin-2-one. 1H NMR (CDCl3) δ7.26-7.10 (m, 5H), 5.68 (m, 1H), 3.83 (m, 1H), 3.54 (m, 1H), 2.69 (m, 2H), 2.30-2.16 (m, 3H), 1.66-1.35 (m, 5H), 0.82 (s, 9H), −0.06 (d, 3H), −0.2 (d, 3H).
