3.1.9. (3*S*,4*S*)-5,8-dihydroxy-4-methoxy-3-pentyl-7-phenylisochroman-1-one (**9**)

To a solution of diMOM-protected methyl derivative **9a** (7.4 mg, 16.8 μmol) in THF (1.0 mL) was added 6 M aqueous HCl (0.50 mL) at 0 ◦C. After stirring for 6 h at room temperature, the reaction was quenched by adding saturated aqueous NaHCO3. 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 phenyl derivative **9** (6.0 mg, 90%) as a yellow solid. m.p. 173–174 ◦C; 1H-NMR (400 MHz, CDCl3) δ 11.21 (1H, s), 7.58 (2H, d, *J* = 7.3 Hz), 7.44 (2H, t, *J* = 7.3 Hz), 7.38 (1H, d, *J* = 7.6 Hz), 7.13 (1H, s), 5.76 (1H, br-s), 4.82 (1H, d, *J* = 2.7 Hz), 4.55 (1H, ddd, *J* = 2.7, 5.1, 8.3 Hz), 3.44 (3H, s), 1.98 (1H, m), 1.89 (1H, m), 1.70–1.40 (2H, overlapped), 1.40–1.25 (4H, overlapped), 0.92 (3H, t, *J* = 6.8 Hz); 13C-NMR (125 MHz, CDCl3) δ 169.5, 153.7, 145.4, 136.2, 131.8, 129.2, 128.3, 127.9, 125.5, 121.1, 107.8, 81.6, 69.6, 56.9, 31.6, 29.8, 24.9, 22.5, 14.0.; IR (KBr) 3307, 2955, 2928, 2859, 1650, 1425, 1295, 1194 cm<sup>−</sup>1; HRMS (ESI) *m*/*z* (M + H)<sup>+</sup> calculated for (C21H25O5) <sup>+</sup> 357.1702, found 357.1707.
