The general procedure for the synthesis of (2S,4S)-4-cyclohexylpyrrolidine-2-carboxylic acid from (2S,4S)-4-phenylpyrrolidine-2-carboxylic acid was as follows: compound V (1.2 g), 5% rhodium-carbon catalyst (0.24 g), concentrated hydrochloric acid (1.2 ml), and methanol (12 ml) were added to the reaction flask sequentially. The reaction mixture was stirred and hydrogenated at 30 °C under 2.0 MPa hydrogen pressure. After 2 hours of reaction, the reaction mixture was filtered under reduced pressure. The filtrate was concentrated under reduced pressure to give a white solid product (1.11 g) in 90.0% yield.
