(Trifluoromethyl)trimethylsilane → (4R)-1-((R)-1-(4-Methoxyphenyl)ethyl)-4-(2,2,2-trifluoro-1-hydroxyethyl)pyrrolidin-2-one

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Reaction Conditions

Reaction Steps

Into a 250-mL 3-necked round-bottom flask purged and maintained with an inert atmosphere of nitrogen was placed a solution of (3R)-1-[(1R)-1-(4-methoxyphenyl)ethyl]-5-oxopyrrolidine-3-carbaldehyde 1.07 (7 g, 28.31 mmol, 1.00 equiv) in toluene (100 mL), trimethyl(trifluoromethyl)silane (2.9 mL), followed by the addition of tetrabutylammonium fluoride (1 mol/L in tetrahydrofuran) (1.53 mL) dropwise with stirring at −60° C. The resulting solution was stirred overnight at room temperature, quenched by the addition of 100 mL of water/ice and extracted with 3×300 mL of ethyl acetate. The organic layers were combined, washed with 3×300 mL of brine, dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was applied onto a silica gel column eluting with dichloromethane: methanol (200:1-80:1) to afford (4R)-1-[(1R)-1-(4-methoxyphenyl)ethyl]-4-(2,2,2-trifluoro-1-hydroxyethyl)pyrrolidin-2-one. The diastereomers were separated by chiral HPLC (CHIRALPAK IC), and the later eluting diastereomer was collected to afford (R)-1-((R)-1-(4-methoxyphenyl)ethyl)-4-((S)-2,2,2-trifluoro-1-hydroxyethyl)pyrrolidin-2-one 1.29. This compound is the earlier diastereomer under RP-HPLC conditions (Gemini column, water/acetonitrile/TFA).

Provenance & Evidence