Boron tribromide → (2R)-11-(3,17beta-dihydroxyestra-1,3,5(10)-trien-7alpha-yl)-2-(3,3,4,4,5,5,6,6,6-nonafluorohexyl)undecanoic acid

Participants

Reaction Conditions

Reaction Steps

Anhydrous dichloromethane (10 ml) was added to (2R)-11-(17β-hydroxy-3-methoxyestra-1,3,5(10)-trien-7α-yl)-2-(3,3,4,4,5,5,6,6,6-nonafluorohexyl)undecanoic acid (358 mg, 0.50 mmol) under nitrogen atmosphere and the resulting mixture was cooled to −78° C. Boron tribromide (1.0 M in tetrahydrofuran, 3.0 ml, 3.0 mmol) was added dropwise to the mixture, which was then stirred on ice for 2.5 hours. The reaction mixture was cooled again to −78° C. and quenched with saturated aqueous sodium bicarbonate over 1 hour. After the reaction mixture was extracted with ethyl acetate, the organic layer was washed sequentially with saturated aqueous potassium bisulfate, saturated aqueous sodium chloride, saturated aqueous sodium bicarbonate and saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, and then filtered. The filtrate was concentrated under reduced pressure using an evaporator and the resulting residue was purified by silica gel column chromatography (Wako gel C-200, eluent: ethyl acetate/n-hexane=4/6) to give (2R)-11-(3,17β-dihydroxyestra-1,3,5(10)-trien-7α-yl)-2-(3,3,4,4,5,5,6,6,6-nonafluorohexyl)undecanoic acid (231 mg, Yield 60%) as a yellow amorphous mass.

Provenance & Evidence