Under argon protection, 1-bromo-3,5-difluorobenzene (1.6 eq.) was dissolved in tetrahydrofuran (THF, 0.26 M) and magnesium chips (1.6 eq.) were added. A reflux condenser was installed and the reaction mixture was immersed in a 90 °C oil bath and refluxed for 2 hours. A THF solution of dihydro-2H-pyran-4(3H)-one (1.0 eq.) was added to the reaction system via syringe. The reaction mixture was stirred at room temperature and under argon protection for 5 hours. After completion of the reaction, the reaction was quenched with saturated ammonium chloride (NH4Cl) solution, the organic phase was extracted with ethyl acetate (EtOAc), washed with saturated sodium chloride (NaCl) solution, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated. Purification by ISCO silica gel column chromatography (0-100% ethyl acetate/n-heptane gradient elution) afforded 4-(3,5-difluorophenyl)tetrahydro-2H-pyran-4-ol in 71% yield.1H NMR (400 MHz, chloroform-d) δppm: 1.59-1.68 (m, 3H), 2.07-2.19 (m, 2H), 3.87- 3.93 (m, 4H), 6.72 (tt, J=8.75, 2.20Hz, 1H), 6.97-7.06 (m, 2H).
