Triethylamine → (S)-tert-butyl 4-(methylthio)-4-oxo-2-(pent-4-enamido)butanoate

Participants

Reaction Steps

Et3N (1.54 ml, 11.0 mmol) and ethyl carbonochloridate (1.05 ml, 11.0 mmol) were added to a solution of the mixed crude product A (1.96 g, 9.68 mmol) of (S)-4-(tert-butoxy)-4-oxo-3-(pent-4-enamido)butanoic acid (Compound 1b-I) and pent-4-enoic acid (1:0.8) in THF (44 ml), and the mixture was stirred at room temperature for 25 minutes. A solution of sodium methanethiolate (1.06 g, 15.1 mmol) in DMF (18 ml) was then added to the reaction mixture, which was stirred at room temperature for 1 hour. Water was then added to the reaction mixture, followed by dilution with dichloromethane. The organic layer was washed with water, and then dried over magnesium sulfate and concentrated under reduced pressure. The resulting residue was purified by reverse-phase silica gel column chromatography (10 mM aqueous ammonium acetate solution/methanol=70/30→40/60) to afford (S)-tert-butyl 4-(methylthio)-4-oxo-2-(pent-4-enamido)butanoate (Compound 1e-IA) (1.38 g, 85%).

Provenance & Evidence