Synthesis
General procedure for the synthesis of (R)-5-bromomethyl-2-pyrrolidinone from (R)-(5-oxopyrrolidin-2-yl)methyl 4-methylbenzenesulfonate: To a solution of (R)-(5-oxopyrrolidin-2-yl)methyl 4-methylbenzenesulfonate (5.0 g, 18.5 mmol) in acetone (10 mL) was added lithium bromide (4.8 g, 55.6 mmol) The reaction mixture was stirred at 80°C overnight. Upon completion of the reaction, the solvent was removed under vacuum and the residue was partitioned between water (50 mL) and ethyl acetate (100 mL). The aqueous layer was extracted with ethyl acetate (2 x 100 mL), the organic phases were combined and dried over anhydrous sodium sulfate. The organic phase was concentrated in vacuo and the residue was purified by column chromatography (using conventional basic activated alumina with the eluent being a mixture of dichloromethane and 0.2-1.0% methanol) to give (R)-5-bromomethyl-2-pyrrolidinone (3.0 g, 90%) as a pale yellow liquid.LCMS (Method F): m/z 178/180 (M + H) + (ES+), retention time 2.24 min, with UV activity.
