Methanesulfonyl chloride → (R)-tert-butyl 4-(tert-butyldimethylsilyloxy)-2-(5-fluoro-2-methoxyphenyl)pyrrolidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of (R)-tert-butyl 2-(tert-butyldimethylsilyloxy)-4-(5-fluoro-2-methoxyphenyl)-4-hydroxybutylcarbamate (4.810 g, 10.84 mmol) in CH2Cl2 (108 mL) at −60° C. was added TEA (4.534 mL, 32.53 mmol) followed by methanesulfonyl chloride (0.9231 mL, 11.93 mmol). The resulting mixture was slowly warmed to −5° C. and poured into a mixture of ice and saturated aqueous NaHCO3 (50 mL). The organic layer was separated and the aqueous layer was extracted with CH2Cl2 (2×50 mL). The combined organic layers were dried over MgSO4, filtered, and concentrated under reduced pressure to give the crude material that was purified by silica column chromatography, eluting with 2-10% MeOH/DCM to afford (R)-tert-butyl 4-(tert-butyldimethylsilyloxy)-2-(5-fluoro-2-methoxyphenyl)pyrrolidine-1-carboxylate (assumed to be a mixture of cis and trans isomers; 2.648 g, 57.38% yield). LC/MS (ES+APCI) m/z=326.1 (M+H-Boc).

Provenance & Evidence