3.1.17. (3*S*,4*S*)-5,8-dihydroxy-7-(hydroxymethyl)-4-methoxy-3-pentylisochroman-1-one (**11**)

To a solution of diMOM hydroxymethyl derivative **11a** (7.2 mg, 24.1 μmol) in MeOH (1.8 mL) was added 6 M aqueous HCl (0.45 mL) at 0 ◦C. After stirring for 4 h at 40 ◦C, 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 = 1:1) to give hydroxymethyl derivative **11** (3.9 mg, 52%) as a white solid. m.p. 143–145 ◦C; 1H-NMR (400 MHz, CDCl3) δ 10.99 (1H, s), 7.12 (1H, s), 6.03 (1H, br-s), 4.74 (1H, d, *J* = 2.4 Hz), 4.72 (2H, br-s), 4.48 (1H, ddd, *J* = 2.4, 5.2, 8.0 Hz), 3.38 (3H, s), 2.53 (1H, br-s), 1.96 (1H, m), 1.86 (1H, m), 1.70–1.50 (1H, overlapped), 1.46 (1H, m), 1.40–1.25 (4H, overlapped), 0.91 (3H, t, *J* = 6.8 Hz); 13C-NMR (125 MHz, CDCl3) δ 169.5, 154.2, 145.8, 130.8, 123.8, 121.4, 107.8, 82.1, 69.8, 61.2, 57.2, 31.9, 30.2, 25.2, 22.8, 14.3.; IR (KBr) 2951, 2921, 2854, 1682, 1440, 1302 cm<sup>−</sup>1; HRMS (ESI) *m*/*z* (M + H)<sup>+</sup> calculated for (C16H23O6) <sup>+</sup> 311.1495, found 311.1498.

3.1.18. ((3*S*,4*S*)-4-methoxy-5,8-bis(methoxymethoxy)-1-oxo-3-pentylisochroman-7-yl) methylmethanesulfonate (**22**)

To a solution of diMOM hydroxymethyl derivative **11a** (7.2 mg, 24.1 μmol) in CH2Cl2 (0.47 mL) were added Et3N (10.8 μL, 77.5 μmol) and MsCl (6.0 μL, 77.5 μmol) at 0 ◦C. After stirring for 40 min at the same temperature, the reaction was quenched by adding water 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 = 2:3) to give diMOM mesylated derivative **22** (30.4 mg, 91%) as a white wax. 1H-NMR (400 MHz, CDCl3) δ 7.51 (1H, s), 5.45 (1H, d, *J* = 12.0 Hz), 5.37 (1H, d, *J* = 12.2 Hz), 5.25 (2H, s), 5.14 (1H, d, *J* = 6.6 Hz), 5.12 (1H, d, *J* = 6.6 Hz), 4.62 (1H, d, *J* = 1.4 Hz), 4.27 (1H, ddd, *J* = 1.2, 5.6, 7.8 Hz), 3.59 (3H, s), 3.50 (3H, s), 3.33 (3H, s), 3.07 (3H, s), 2.03 (1H, m), 1.82 (1H, m), 1.58 (1H, m), 1.44 (1H, m), 1.40–1.25 (4H, overlapped), 0.91 (3H, t, *J* = 6.8 Hz); 13C-NMR (100 MHz, CDCl3) δ 161.9, 152.2, 150.5, 131.3, 130.5, 120.3, 119.7, 102.8, 95.5, 81.2, 68.6, 66.9, 58.1, 57.4, 56.9, 38.2, 31.9, 30.9, 25.2, 22.8, 14.3.; IR (KBr) 2958, 2930, 2860, 1829, 1681, 1440, 1358, 1175, 933 cm<sup>−</sup>1; HRMS (ESI) *m*/*z* (M + Na)<sup>+</sup> calculated for (C21H32O10SNa)<sup>+</sup> 499.1614, found 499.1616.
