To a 250 mL multi-necked round-bottomed flask was added 8.1 g (30.8 mmol) of 1-benzyl 3-methylpyrrolidine-1,3-dicarboxylate and 80 mL of tetrahydrofuran, and 80 mL of an aqueous solution of lithium hydroxide of 3.9 g (92.4 mmol) was added slowly dropwise.The reaction mixture was stirred for 1 hr at 0 °C, followed by stirring at room temperature overnight. Upon completion of the reaction, the mixture was washed with ether and the pH of the mixture was adjusted to 5-6 with 0.5 M hydrochloric acid. the mixture was extracted three times with 30 mL of ethyl acetate, and the organic phases were combined. The organic phase was dried with anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to give 7.3 g of 1-Cbz-3-pyrrolidinecarboxylic acid as a yellow oil in 95% yield.
