Correction to “Concise and Stereoselective Total Syntheses of Annotinolides C, D, and E”

We wish to clarify that because we have not determined the absolute configuration of our isolated individual enantiomers (of compounds such as 40 and 41), we have drawn these species with the same relative orientation so as not to imply a defined identity for them.

In addition, following the initial appearance of this work, we realized that the hydride transfer converting 26 into 27, as drawn in Scheme 3, would actually reflect a [1,4]-hydride transfer, which, while known, is generally rare. An alternate explanation for the observed outcome could be a [1,6]-hydride transfer pathway. For this manifold to be active, Et₃B would need to react with the free alcohol to form a borinate, followed by intramolecular hydrogen abstraction of a C–H atom on a methylene adjacent to the boron. See, for example, ref (1).

Scheme 3. Completion of the [3.2.1]-Core of the Annotinolides.

Reagents and conditions: (a) CeCl₃·7H₂O (1.2 equiv), NaBH₄ (1.5 equiv), MeOH (0.1 M), 0 to 23 °C, 0.5 h, 84%; (b) 2,6-lutidine (5.0 equiv), TBSOTf (1.5 equiv), CH₂Cl₂ (0.1 M), 23 °C, 4 h, 86%; (c) Pd(PPh₃)₄ (0.4 equiv), pyrrolidine (1.2 equiv), MeCN (0.1 equiv), 0 to 23 °C, 1 h, 82%; (d) DPPA (1.0 equiv), Et₃N (2.0 equiv), toluene (0.1 M), 23 °C, 0.5 h; then 110 °C, 1 h; then t-BuOK (2.0 equiv), 23 °C, 1 h, 82%; (e) DIBAL-H (4.0 equiv), toluene, 0 °C, 15 min, 85%; (f) NaH₂PO₄·2H₂O (20 equiv), NaClO₂ (10 equiv), t-BuOH/H₂O/2-methyl-2-butene = 3:3:1 (0.05 M), 23 °C, 40 min, 95%; (g) NIS (10 equiv), CH₂Cl₂, 23 °C, 6 h, 74%; (h) n-Bu₃SnH (1.5 equiv), Et₃B (1.0 equiv), air, toluene (0.05 M), 0 °C, 15 min, 91%; (i) TBAF (1.0 equiv), THF (0.1 M), 0 °C, 15 min, 92%; (j) n-Bu₃SnH (1.5 equiv), Et₃B (1.0 equiv), air, toluene (0.05 M), 0 °C, 15 min, 98%; (k) Dess–Martin periodinane (2.0 equiv), NaHCO₃ (10.0 equiv), CH₂Cl₂ (0.05 M), 23 °C, 30 min, 93%; (l) [CuH(Ph₃P)]₆ (0.5 equiv), toluene (0.5 M), 23 °C, 1 h, 60%.