(4S)-4-[(1R)-1-carboxy-but-3-enyl]-2,2-dimethyl-1,3-dioxolan-5-one → (2R)-N-[(1S)-1-[(benzyloxy)carbonyl]-2,2-dimethylpropyl]-2-[(4S)-2,2-dimethyl-5-oxo-1,3-dioxolan-4-yl]pent-4-enamide

Participants

Reaction Steps

According to the method of Preparation 2, (4S)-4-[(1R)-1-carboxy-but-3-enyl]-2,2-dimethyl-1,3-dioxolan-5-one (Preparation 14b)(2.39 g, 11.20 mmol) was reacted with L-tert-leucine benzyl ester hydrochloride (3.03 g, 11.76 mmol) for 1 h at 4° C. and then 17 h at 20° C. The mixture was concentrated under reduced pressure, dissolved in ethyl acetate (200 mL), washed with 0.5M aqueous sodium dihydrogenphosphate (2×200 mL), 5% saturated sodium bicarbonate (200 mL), water, dried (MgSO4), and concentrated under reduced pressure. The residue was purified by flash chromatography (gradient elution with hexane:ethyl acetate 10:1 to 1:1) to give (2R)-N-[(1S)-1-[(benzyloxy)carbonyl]-2,2-dimethylpropyl]-2-[(4S)-2,2-dimethyl-5-oxo-1,3-dioxolan-4-yl]pent-4-enamide (4.06 g, 87%), as a white solid.

Provenance & Evidence