Ammonium Chloride → (R)-tert-butyl 2-(tert-butyldimethylsilyloxy)-4-(5-fluoro-2-methoxyphenyl)-4-hydroxybutylcarbamate

Participants

Reaction Conditions

Reaction Steps

To a solution of (R)-tert-butyl 4-(tert-butyldimethylsilyloxy)-2-oxopyrrolidine-1-carboxylate (6.00 g, 19.0 mmol) in THF (36 mL) at 0° C. was added a 0.5 M solution of (5-fluoro-2-methoxyphenyl)magnesium bromide in THF (50.0 mL, 25.0 mmol). The resulting mixture was stirred at 0° C. for 30 minutes, then treated with MeOH (60 mL) and NaBH4 (0.966 g, 25.2 mmol). After stirring at 0° C. for an additional 30 minutes, the reaction mixture was poured into saturated aqueous NH4Cl (40 mL) and extracted with EtOAc (2×50 mL). The combined organic layers were washed with brine, dried over MgSO4, filtered, and concentrated under reduced pressure to give the crude material which was purified by silica column chromatography, eluting with 0-2% MeOH/DCM to afford (R)-tert-butyl 2-(tert-butyldimethylsilyloxy)-4-(5-fluoro-2-methoxyphenyl)-4-hydroxybutylcarbamate (which was assumed to be a mixture of the syn and anti isomers), (4.81 g, 57.0% yield). 1H NMR (CDCl3) δ 7.20 (m, 1H), 6.90 (m, 1H), 6.77 (m, 1H), 5.12 (m, 1H), 4.10 (m, 1H), 3.82 (m, 3H), 3.29 (m, 2H), 1.71-1.93 (m, 2H), 1.45 (s, 9H), 0.93 (d, 9H), 0.11-0.14 (m, 6H).

Provenance & Evidence