[Synthesis]
(a) Step 1 was synthesized with reference to known literature (). 4-Bromoresorcinol (0.42 g, 2.2 mmol) was dissolved in 1,2-dimethoxyethane (10 mL), phenylboronic acid (0.37 g, 3.0 mmol) and 2M aqueous sodium carbonate solution (3.5 mL) were added sequentially and the mixture was stirred at room temperature. Under argon protection, tetrakis(triphenylphosphine)palladium(0) (0.14 g, 0.12 mmol) was added to the reaction system, followed by placing the reaction mixture in a sealed tube and stirring the reaction for 6 hours at 95 °C. After completion of the reaction, ice water was added to the mixture and extracted with ethyl acetate. The organic layer was washed sequentially with water and saturated saline and dried over anhydrous magnesium sulfate. The solvent was removed by concentration under reduced pressure and the residue was purified by silica gel column chromatography with hexane/ethyl acetate (75:25) as eluent to afford [1,1'-biphenyl]-2,4-diol (0.25 g, 61% yield).1H NMR (300 MHz, DMSO-d6) δ 6.30 (dd, J = 2.2 Hz, 8.8 Hz, 1H), 6.40 (d, J = 2.2 Hz, 1H), 7.04 (d, J = 8.8 Hz, 1H), 7.20 (m, 1H), 7.33 (m, 2H), 7.47 (d, J = 7.3 Hz, 2H), 9.31 (s, 1H), 9.34 (s, 1H). |