Boron tribromide → HCID 72195241, compound

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Reaction Steps

To (R)-2-(1-(benzyloxy)ethyl)-3-(3-fluorophenyl)-4H-chromen-4-one (5.0 g, 13.35 mmol) in dichloromethane (50 ml) cooled to −78° C., boron tribromide (1M in dichloromethane, 36.5 ml, 0.145 mmol) was added dropwise and stirred for 1 h. The reaction mixture was quenched with 2N HCl solution, extracted with dichloromethane, dried over sodium sulphate and concentrated under reduced pressure. The crude product was purified by column chromatography with ethyl acetate:petroleum ether to afford (R)-3-(3-fluorophenyl)-2-(1-hydroxyethyl)-4H-chromen-4-one as an off-white solid (3.05 g, 80%). 1H-NMR (6 ppm, CDCl3, 400 MHz): 8.24 (dd, J=7.9, 1.5 Hz, 1H), 7.73 (m, 1H), 7.54 (d, J=8.1 Hz, 1H), 7.44 (m, 2H), 7.13-7.01 (m, 3H), 4.71 (q, J=6.6 Hz, 1H), 1.56 (d, J=6.5 Hz, 3H). Mass: 284.9 (M+). Purity: 99.73%. [α]25D −0.605 (c=1, CHCl3). Enantiomeric excess: 95.2%, enriched in the late eluting isomer (retention time: 10.19 min.) as determined by HPLC on a chiralpak AD-H column.

Provenance & Evidence