Hydrochloric Acid → methyl (R)-2-oxo-1-phenyl-2-((S)-2-(5-(4-(6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-2-yl)phenyl)-1H-imidazol-2-yl)pyrrolidin-1-yl)ethylcarbamate

Participants

Reaction Steps

A solution of hydrogen chloride in dioxane (4 N, 5 mL) was added to a solution of (S)-tert-butyl 2-(5-(4-(6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-2-yl)phenyl)-1H-imidazol-2-yl)pyrrolidine-1-carboxylate (328 mg, 0.56 mmol) in dichloromethane (5 mL). Gas evolution was observed. After 20 min the solvent was removed under reduced pressure and the residue was placed under high vacuum for 30 min. The solid was taken up in N,N-dimethylformamide (3 mL) and N-methylmorpholine (158 μL, 1.43 mmol) was added to the solution. In a separate vessel, COMU (258 mg, 0.605 mmol), and N-methylmorpholine (158 μL, 1.43 mmol) were added to a solution of (R)-2-(methoxycarbonylamino)-2-phenylacetic acid (126 mg, 0.604 mmol) in dichloromethane (3 mL). This was stirred for 5 minutes and both solutions were combined. After 15 minutes the mixture was diluted with ethyl acetate (20 mL) and washed with water (5 mL) and brine (5 mL). The organic phase was dried over sodium sulfate and filtered. The solvent was removed under reduced pressure and the residue was subjected to flash chromatography with eluant of (10% methanol in ethyl acetate) and hexane. The product containing fractions were combined and the solvent was removed under reduced pressure to provide methyl (R)-2-oxo-1-phenyl-2-((S)-2-(5-(4-(6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzo[b]thiophen-2-yl)phenyl)-1H-imidazol-2-yl)pyrrolidin-1-yl)ethylcarbamate (261 mg, 0.39 mmol, 69%).

Provenance & Evidence