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. Author manuscript; available in PMC: 2024 Aug 16.
Published in final edited form as: J Am Chem Soc. 2023 Aug 1;145(32):17919–17925. doi: 10.1021/jacs.3c05383

Scheme 6.

Scheme 6.

Short synthesis of (±)-echinolactone D (29) enabled by a palladium-catalyzed stitching strategy.a,b

aReagents and conditions: (1) Pd(CH3CN)4(BF4)2 (20 mol%), L1 (20 mol%), L6 (20 mol%), AgOAc (2.0 equiv), HFIP, 80 °C; (2) LiOH (5.0 equiv), THF−H2O−MeOH (1:1:1 v/v), 50 °C; (3) Pd(OAc)2 (2 mol%), L7 (4 mol%), ethylene oxide (2.0 equiv), KOAc (1.0 equiv), HFIP, 75 °C; (4) TBCA (0.35 equiv), TFA, 0→23 °C; (5) Pd(dppf)Cl2 (20 mol%), MeBF3K (1.5 equiv), KOH (3.0 equiv), Dioxane−H2O (5:1 v/v), 100 °C; (6) H2SO4 (20.0 equiv), AcOH, 90 °C; (7) BH3•DMSO (1.5 equiv), THF, 0→23 °C. bTBCA = Tribromoisocyanuric acid.