3.1.19. (3*S*,4*S*)-7-(azidomethyl)-4-methoxy-5,8-bis(methoxymethoxy)-3-pentylisochroman-1-one (**13a**)

To a solution of diMOM mesylated derivative **22** (5.3 mg, 11.1 μmol) in DMF (55 μL) was added NaN3 (0.79 mg, 12.1 μmol) at room temperature. After stirring for 6 h 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 = 3:7) to give diMOM azide derivative **13a** (3.7 mg, 79%) as a pale-yellow oil. 1H-NMR (500 MHz, CDCl3) δ 7.44 (1H, s), 5.26 (1H, d, *J* = 6.9 Hz), 5.25 (1H, d, *J* = 6.9 Hz), 5.13 (1H, d, *J* = 6.9 Hz), 5.11 (1H, d, *J* = 6.9 Hz), 4.65 (1H, d, *J* = 14.5 Hz), 4.62 (1H, d, *J* = 1.3 Hz), 4.53 (1H, d, *J* = 14.5 Hz), 4.27 (1H, ddd, *J* = 1.3, 5.7, 7.3 Hz), 3.60 (3H, s), 3.51 (3H, s), 3.32 (3H, s), 2.04 (1H, m), 1.82 (1H, m), 1.65–1.50 (1H, overlapped), 1.43 (1H, m), 1.40–1.30 (4H, overlapped), 0.91 (3H, t, *J* = 7.0 Hz); 13C-NMR (125 MHz, CDCl3) δ 162.2, 152.1, 150.5, 133.5, 129.1, 119.7, 119.5, 102.6, 95.5, 81.2, 68.6, 57.9, 57.3, 56.8, 50.2, 31.9, 30.9, 25.2, 22.9, 14.4.; IR (KBr) 2957, 2928, 2858, 2829, 2105, 1729, 1153, 1009 cm<sup>−</sup>1; HRMS (ESI) *m*/*z* (M + H)<sup>+</sup> calculated for (C20H30N3O7) + 424.2084, found 424.2085.
