Cesium fluoride → (2R,3S)-3-(tert-Butyl-dimethylsilanyloxy)-2-[(1S)-(2,2,2-trifluoro-1-hydroxyethyl)]pyrrolidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To 75A (1.00 g, 3.04 mmol) was added trimethyl(trifluoromethyl)silane (550 mg, 3.87 mmol) and cesium fluoride (10 mg, dried under high vacuum at 130° C. for 12 h). The mixture was stirred at rt for 24 h, and then was heated to 50° C. for 5 h. After cooling to rt, 4N HCl (ca. 10 mL) was added and the reaction was stirred overnight. The product was extracted with EtOAc (3×30 mL). The organic layer was washed with saturated aqueous NaHCO3 and brine, then dried (MgSO4), filtered and concentrated. The residue was purified via flash chromatography eluting with 0-15% ethyl acetate/hexane to provide (2R,3S)-3-(tert-butyl-dimethyl-silanyloxy)-2-[(1R)-(2,2,2-trifluoro-1-hydroxy-ethyl)]-pyrrolidine-1-carboxylic acid tert-butyl ester (75B) (357 mg) as a colorless oil and (2R,3S)-3-(tert-butyl-dimethylsilanyloxy)-2-[(1S)-(2,2,2-trifluoro-1-hydroxyethyl)]pyrrolidine-1-carboxylic acid tert-butyl ester (75C) (380 mg) as a white solid.

Provenance & Evidence