(R)-N-methoxy-1-((R)-1-(4-methoxyphenyl)ethyl)-N-methyl-5-oxopyrrolidine-3-carboxamide → (R)-4-acetyl-1-((R)-1-(4-methoxyphenyl)ethyl)pyrrolidin-2-one

A solution of (R)-N-methoxy-1-((R)-1-(4-methoxyphenyl)ethyl)-N-methyl-5-oxopyrrolidine-3-carboxamide 1.02 (6.87 g, 22.4 mmol) in THF (70 mL) was cooled to an internal temperature of 19° C. under Ar. Methylmagnesium bromide (3 M in Et2O, 14.9 mL, 44.7 mmol) was added in portions over ca. 10 min to keep the internal temperature below 10° C. The resulting mixture was stirred for 1 h, by which time the internal temperature had reached −12° C., and was then warmed in an ice bath to 0° C. After an additional 50 min, the reaction was quenched with saturated aqueous NH4Cl (150 mL) and was diluted with EtOAc (150 mL) and water to dissolve solids. The phases were separated, and the aqueous phase was extracted with EtOAc (100 mL). The combined organic phase was dried over Na2SO4, filtered, and concentrated onto 25 g silica gel. The product was purified by silica gel chromatography (15% to 45% acetone in hexanes) to afford (R)-4-acetyl-1-((R)-1-(4-methoxyphenyl)ethyl)pyrrolidin-2-one 1.03.