The general procedure for the synthesis of N-Boc-3-acetylpyrrolidine from tert-butyl 3-(methoxy(methyl)carbamoyl)pyrrolidine-1-carboxylate and methylmagnesium bromide was as follows: tert-butyl 3-(methoxy(methyl)carbamoyl)pyrrolidine-1-carboxylate (4.0 g, 15.50 mmol) was dissolved in THF (70 ml) at 0 °C and under nitrogen protection and stirred. . 3M methylmagnesium bromide ether solution (26 ml, 78 mmol) was added slowly dropwise, keeping the reaction temperature at 0 °C. After the dropwise addition, the reaction mixture was continued to be stirred at 0°C for 30 minutes. Subsequently, the reaction mixture was slowly poured into saturated ammonium chloride solution (1 L) to quench the reaction and extracted with ethyl acetate (2 x 200 ml). The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to afford the crude product tert-butyl 3-acetylpyrrolidine-1-carboxylate (3.0 g, 14.08 mmol), which was used directly in the subsequent reaction without further purification. The product was analyzed by LCMS (Method A) with a retention time of 3.83 min, and the mass spectrum (ES+) showed m/z of 157.89 (M-56).1H NMR (400 MHz, DMSO-d6) δ ppm: 3.77-3.40 (m, 2H), 3.22-3.25 (m, 3H), 2.17 (s, 3H), 2.03- 2.11 (m, 1H), 1.85-1.94 (m, 1H), 1.39 (s, 9H).
