Diisopropylethylamine → [1-(5-Cyclopentylmethyl-isoxazol-3-ylcarbamoyl)-butyl]-carbamic acid tert-butyl ester

Participants

Reaction Steps

(S)-2-tert-Butoxycarbonylamino-pentanoic acid (21.7 mmol) was dissolved in 100 mL of dichloromethane at rt under N2. Diisopropylethylamine (43.3 mmol) was added, followed by PyBOP (32.5 mmol). The reaction was stirred for 10 minutes at rt. The isoxazole R (21.7 mmol) was separately dissolved in 25 mL of dichloromethane and then added to the reaction solution. The resultant mixture was stirred at rt for 36-48 hours. The crude material was then diluted in 200 mL EtOAc and washed with two 100 mL portions of water, followed by 100 mL of brine. The organics were then dried over Na2SO4, filtered and concentrated under reduced pressure. The crude products were purified through flash chromatography on silica gel to give [1-(5-Cyclopentylmethyl-isoxazol-3-ylcarbamoyl)-butyl]-carbamic acid tert-butyl ester (14.0 mmol).

Provenance & Evidence