1-Benzyl-3-methylpyrrolidin-2-one (0.323 g, 1.7 mmol, 1.0 eq.) was used as a starting material and dissolved in toluene (2 mL, 1 M). Trifluoromethanesulfonic acid (0.604 mL, 6.8 mmol, 4.0 eq.) was added to this solution. The reaction mixture was placed in a microwave reactor and heated at 195°C for 25 minutes. Upon completion of the reaction, the mixture was poured into a small amount of saturated aqueous sodium bicarbonate solution for neutralization. The aqueous phase was extracted with ethyl acetate and the organic phase was again washed with saturated aqueous sodium chloride solution. The combined aqueous phases were again extracted with ethyl acetate. All organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated in vacuum. The crude product was purified by silica gel column chromatography with a gradient of dichloromethane solution of 0-10% methanol as eluent to give 3-methyl-2-pyrrolidinone (0.087 g). The structure of the product was confirmed by 1H NMR (300 MHz, CDCl3): δ 6.49 (br s, 1H), 3.37-3.26 (m, 2H), 2.53-2.28 (m, 2H), 1.80-1.65 (m, 1H), 1.21-1.19 (d, 3H, J = 6.6 Hz).
