Pyridine → methyl 3-(S)-n-butyl-3-[2-(S)-tert-butoxycarbonylpyrrolidin-1-ylcarbonyl)-2-(R)-fluoropropionate

Participants

Reaction Conditions

Reaction Steps

To methyl 3-(R)-n-butyl-3-[2-(S)-tert-butoxycarbonylpyrrolidin-1-ylcarbonyl)-2-(S)-hydroxypropionate G-3 (5 mmol) in DCM (5 mL) was added pyridine (15 mmol), the reaction was cooled to −20° C., then triflic anhydride was added (7.5 mmol). The solution was stirred for 1 hour, then washed with aqueous citric acid, sodium bicarbonate and brine, then dried (Na2SO4) and concentrated. The intermediate triflate was then resuspended in DCM and cooled to −50° C. Tris(dimethylamino)sulfur (trimethylsilyl)difluoride (TAS-F) was added (5 mmol) and the solution allowed to warm to rt. The reaction mixture was washed with aqueous sodium bicarbonate and brine, dried (Na2SO4) and concentrated then purified on silica gel (ethylacetate/hexanes) to afford 2.3 mmol (45%) of methyl 3-(S)-n-butyl-3-[2-(S)-tert-butoxycarbonylpyrrolidin-1-yl-carbonyl)-2-(R)-fluoropropionate G-4.

Provenance & Evidence