General procedure for the synthesis of 1-benzyl-3-(Boc-amino)pyrrolidine from di-tert-butyl dicarbonate and 1-benzylpyrrolidin-3-amine: 1-benzylpyrrolidin-3-amine (10 g, 57 mmol) was dissolved in 3M aqueous sodium hydroxide (21 ml) and tertiary butyl alcohol (114 ml) in a 500 ml reaction vessel. Di-tert-butyl dicarbonate (Boc2O; 13.07 g, 59.9 mmol) was slowly added to the above solution under stirring conditions. The reaction mixture was stirred at room temperature for 12 hours. After completion of the reaction, the reaction mixture was extracted with ethyl acetate (2×). The organic layers were combined and washed sequentially with 0.1 N hydrochloric acid solution and saturated brine, then dried with anhydrous sodium sulfate. After filtration, the filtrate was concentrated under reduced pressure. The crude product obtained was purified by silica gel column chromatography to afford 15.25 g of 1-benzyl-3-(Boc-amino)pyrrolidine as a white solid (97% yield). The structure of the product was confirmed by 1H-NMR (200 MHz, CDCl3) and LC/MS (M+H: 277).
