Boron trifluoride etherate → (r)-n-(1-(4-Fluoro-3-methoxyphenyl)-1-(3-fluoro-5-(1,1,2,2-tetrafluoroethoxy)phenyl)-2-phenylethyl)-2-methylpropane-2-sulfinamide

Participants

Reaction Steps

To a solution of (R)-N-((4-fluoro-3-methoxyphenyl)(3-fluoro-5-(1,1,2,2-tetrafluoroethoxy)phenyl)methylene)-2-methylpropane-2-sulfinamide (4.4 g, 9.42 mmol) in CH2Cl2 (190 mL, 0.05 M) at −71° C. was added BF3.Et2O (2.37 mL, 18.8 mmol). The reaction mixture was stirred for 10 min and BnMgCl (25 mL, 1N in Et2O, 26 mmol) was added. The reaction mixture was stirred at −75° C. for an additional 5 min, and quenched by the addition of saturated NH4Cl. The organic portion was separated, washed by H2O, dried over Na2SO4 and filtered. The solvent was then removed under reduced pressure and the residue was purified by ISCO chromatography using hexanes/EtOAc (0-80%) to give (R)-N-(1-(4-fluoro-3-methoxyphenyl)-1-(3-fluoro-5-(1,1,2,2-tetrafluoroethoxy)phenyl)-2-phenylethyl)-2-methylpropane-2-sulfinamide as a mixture of two diastereomers. The mixture (1 to 4 ratio) was then separated by chiral AD column using 20% IPA/hep/0.15 DEA as mobile phase to afford (R)-N-((S)-1-(4-fluoro-3-methoxyphenyl)-1-(3-fluoro-5-(1,1,2,2-tetrafluoroethoxy)phenyl)-2-phenylethyl)-2-methylpropane-2-sulfinamide (0.79 g, 15% yield). LCMS: RT=2.09 min, [M+H] 560.2 (Phenomenex Luna C18 column, 4.6×30 mm eluting with 10-90% MeOH/H2O over 2 minutes containing 0.1% TFA; 5 mL/min, monitoring at 220 nm).

Provenance & Evidence