Ethyl Acetate → (S)-N-((S)-2-(5-bromo-2-fluorophenyl)-1,1-difluoro-4-hydroxybutan-2-yl)-2-methylpropane-2-sulfinamide

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Reaction Conditions

Reaction Steps

(S)-methyl 3-(5-bromo-2-fluorophenyl)-3-((S)-1,1-dimethylethylsulfinamido)-4,4-difluorobutanoate (intermediate E3.1) (1.65 g, 3.83 mmol) was dissolved in tetrahydrofuran (80 ml) and lithium borohydride (668 mg, 30.7 mmol) was added at 5° C. in two portions. The turbid solution was stirred at 23° C. for 16 hours. The reaction mixture was poured into ice water and ethyl acetate was added. Saturated NH4Cl solution (50 ml) was added slowly and the mixture was stirred vigorously for 45 min until the gas evolution finished. The organic layer was separated, dried over Na2SO4, filtered and evaporated to give a yellow oil. The residue was purified by chromatography on 50 g silica gel with ethyl acetate/heptane 0-80% to give (S)—N—((S)-2-(5-bromo-2-fluorophenyl)-1,1-difluoro-4-hydroxybutan-2-yl)-2-methylpropane-2-sulfinamide (815 mg, 2.03 mmol, 52.8% yield) as a colourless oil. MS (ISN): m/z=399.9 [M−H]− and 401.9 [M+2−H]−.

Provenance & Evidence