Cyclopentanone → methyl (2S)-2-(cyclopentylamino)butanoate

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence