Figure 8: The oxidative Heck annulation approach towards the total syntheses of oridamycins A and B. | Nature Communications

Figure 8: The oxidative Heck annulation approach towards the total syntheses of oridamycins A and B.

From: Total synthesis and antiviral activity of indolosesquiterpenoids from the xiamycin and oridamycin families

Figure 8

Reagents and conditions: (a) PhSO2Cl (2.0 eq), Bu4NBr (10 mol%), aq. NaOH (50 wt%)/toluene (1:2), 22 °C, 3 h; (b) SeO2 (20 mol%), tBuOOH (2.0 eq), CH2Cl2, 0 °C, 10 h, 78% (two steps); (c) Et3N (1.5 eq), MsCl (1.2 eq), LiBr (5.0 eq), THF, 0 °C, 30 min; (d) 39, (1.0 eq), KH (1.2 eq), BuLi (1.2 eq), THF/HMPA (5:1), 0 °C, 3 h, 80% (two steps); (e) Mn(OAc)3·2H2O (2.0 eq), Cu(OAc)2·H2O (1.0 eq), DMSO, 22 °C, 12 h, 52%; (f) Mg (3.0 eq), NH4Cl (1.2 eq), MeOH, 22 °C, 1 h, 96%; (g) Pd(OAc)2 (20 mol%), p-benzoquinone (2.5 eq), AcOH/toluene (1:4), 50 °C, 2 h, 65%; (h) NaBH4 (3.0 eq), CeCl3·7H2O (3.0 eq), MeOH, 0 °C, 30 min; (i) TASF (2.0 eq), DMF, 50 °C, 2 h, 85% (two steps); (j) NH2OMe·HCl (2.0 eq), pyridine, 22 °C, 2 h, 93%; (k) Boc2O (2.0 eq), 4-DMAP (2.0 eq), THF, 22 °C, 1 h, 89%; (l) Pd(OAc)2 (20 mol%), PhI(OAc)2 (1.1 eq), Ac2O/AcOH (1:1), 110 °C, 1 h, 81%; (m) aq. HClO4 (6.0 M)/acetone (1:3), 22 °C, 8 h; (n) NaBH4 (3.0 eq), MeOH, 0 °C, 30 min, 54% (two steps); (o) TASF (2.0 eq), DMF, 50 °C, 2 h, 91%.

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