Aluminum(III) Chloride → 4H-1-Benzopyran-4-one, 6-fluoro-3-(3-fluorophenyl)-2-[(1R)-1-hydroxyethyl]-

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Reaction Steps

To (R)-2-(1-(benzyloxy)ethyl)-6-fluoro-3-(3-fluorophenyl)-4H-chromen-4-one (10.5 g, 26.69 mmol) in Dichloromethane (110 ml) cooled to 0° C., anhydrous Aluminium chloride (5.35 g, 40.03 mmol) was added portion wise and stirred for 1 h and then at RT for 2 h. The reaction mixture was quenched with dilute aq. HCl (10 ml), extracted with Dichloromethane (2×50 ml). The organic layer was dried over sodium sulphate and concentrated under reduced pressure. The crude product was purified by column chromatography with ethyl acetate:petroleum ether to afford the title compound as off-white solid (6.5 g, 81%). 1H-NMR (δ ppm, CDCl3, 400 MHz): 7.86 (dd, J=8.3, 3.0 Hz, 1H), 7.56 (dd, J=9.2, 4.2 Hz, 1H), 7.45 (m, 2H), 7.12-6.99 (m, 3H), 4.76 (q, J=6.6 Hz, 1H), 1.55 (d, J=6.6 Hz, 3H). Mass: 303.2 (M++1). Purity: 99.78%. [α]25D 0.287 (c=1, CHCl3). Enantiomeric excess: 97.74%, enriched in the late eluting isomer (retention time: 10.93 min.) as determined by HPLC on a chiralpak AD-H column.

Provenance & Evidence