3.1.11. (3*S*,4*S*)-7-([1,1'-biphenyl]-4-yl)-5,8-dihydroxy-4-methoxy-3-pentylisochroman-1-one (**10**)

To a solution of diMOM-protected biphenyl derivative **10a** (12.9 mg, 24.8 μmol) in THF (1.7 mL) was added 6 M aqueous HCl (0.83 mL) at 0 ◦C. After stirring for 17 h at room temperature, the reaction was quenched by adding saturated aqueous NaHCO3 at 0 ◦C. The mixture was extracted with EtOAc (×3) and the combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified with PTLC (EtOAc:*n*-hexane = 3:7) to give biphenyl derivative **10** (9.9 mg, 92%) as a yellow solid. m.p. 181–182 ◦C; 1H-NMR (400 MHz, CDCl3) δ 11.28 (1H, s), 7.67 (4H, s), 7.64 (2H, d, *J* = 7.3 Hz), 7.46 (2H, t, *J* = 7.3 Hz), 7.37 (1H, t, *J* = 7.3 Hz), 7.19 (1H, s), 5.75 (1H, br-s), 4.84 (1H, d, *J* = 2.7 Hz), 4.56 (1H, ddd, *J* = 2.7, 5.4, 8.3 Hz), 3.46 (3H, s), 1.98 (1H, m), 1.89 (1H, m), 1.70–1.50 (2H, overlapped), 1.45–1.25 (4H, overlapped), 0.92 (3H, t, *J* = 6.8 Hz); 13C-NMR (125 MHz, CDCl3) δ 169.4, 153.8, 145.5, 140.7, 135.2, 131.4, 129.6, 128.8, 127.5,127.15, 127.07, 125.3, 121.0, 107.9, 81.5, 69.8, 56.9, 31.6, 29.8, 24.9, 22.5, 14.0.; IR (KBr) 3283, 2954, 2929, 2863, 1668, 1595, 1295, 1220, 772 cm<sup>−</sup>1; HRMS (ESI) *m*/*z* (M + Na)<sup>+</sup> calculated for (C27H28O5Na)<sup>+</sup> 455.1834, found 455.1831.
