左乙拉西坦杂质19

反应条件: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Methyl (2S)-2-aminobutanoate 41b (18.74 g, 0.12 mol) was dissolved in 280 mL of dichloromethane. The reaction solution was cooled down to 0° C. in an ice-water bath followed by the addition of sodium acetate (5 g, 0.061 mol), cyclopentanone (10.78 g, 0.13 mol) and sodium triacetoxyborohydride (31 g, 0.16 mol) successively. The reaction solution was heated to room temperature and stirred for 4 hours. The reaction solution was poured into 150 mL of water, added dropwise with saturated sodium carbonate solution to adjust pH to 11 to 12 and seperated. The aqueous phase was extracted with dichloromethane (150 mL×2). The combined organic phase was washed with saturated brine (100 mL×2), then dried over anhydrous magnesium sulfate, filtered and the filtrate was concentrated under reduced pressure to obtain the title compound methyl (2S)-2-(cyclopentylamino)butanoate 4k (17.42 g, yield: 77.1%) as a light yellow oil. The reaction solution was heated to room temperature seperated The aqueous phase was extracted with dichloromethane (150 mL×2) The combined organic phase was washed with saturated brine (100 mL×2) dried over anhydrous magnesium sulfate filtered the filtrate was concentrated under reduced pressure

反应条件: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

实验步骤: Methyl (2S)-2-aminobutanoate 41b (18.74 g, 0.12 mol) was dissolved in 280 mL of dichloromethane. The reaction solution was cooled down to 0° C. in an ice-water bath followed by the addition of sodium acetate (5 g, 0.061 mol), cyclopentanone (10.78 g, 0.13 mol) and sodium triacetoxyborohydride (31 g, 0.16 mol) successively. The reaction solution was heated to room temperature and stirred for 4 hours. The reaction solution was poured into 150 mL of water, added dropwise with saturated sodium carbonate solution to adjust pH to 11 to 12 and seperated. The aqueous phase was extracted with dichloromethane (150 mL×2). The combined organic phase was washed with saturated brine (100 mL×2), then dried over anhydrous magnesium sulfate, filtered and the filtrate was concentrated under reduced pressure to obtain the title compound methyl (2S)-2-(cyclopentylamino)butanoate 4k (17.42 g, yield: 77.1%) as a light yellow oil. The reaction solution was heated to room temperature seperated The aqueous phase was extracted with dichloromethane (150 mL×2) The combined organic phase was washed with saturated brine (100 mL×2) dried over anhydrous magnesium sulfate filtered the filtrate was concentrated under reduced pressure