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. 2013 May 3;52(19):5046-51.
doi: 10.1002/anie.201301018. Epub 2013 Apr 3.

Cu-catalyzed chemoselective preparation of 2-(pinacolato)boron-substituted allylcopper complexes and their in situ site-, diastereo-, and enantioselective additions to aldehydes and ketones

Fanke Meng  1 , Hwanjong Jang, Byunghyuck Jung, Amir H Hoveyda
Affiliations

Cu-catalyzed chemoselective preparation of 2-(pinacolato)boron-substituted allylcopper complexes and their in situ site-, diastereo-, and enantioselective additions to aldehydes and ketones

Fanke Meng et al. Angew Chem Int Ed Engl. .
No abstract available

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Figures

Scheme 1
Scheme 1
Chemoselective Cu–B addition to an allene, followed by site-, diastereo- and enantioselective addition of the resulting 2-(pinacolato)boron-substituted allylcopper species to aldehydes and ketones would lead to a range of valuable organic molecules by a catalytic multi-component operation; B(pin) = (pinacolato)boron, L = ligand.
Scheme 2
Scheme 2
Products from sequential 2-B(pin)-substituted allylcopper formation/aldehyde addition/oxidation reactions catalyzed by rac-binap–Cu complex. [a] Reactions performed with 4.0 mol % rac-binap, 4.0 mol % CuCl and 16 mol % NaOtBu under otherwise the same conditions as shown in Table 1, except 5.0 and 2.0 equiv. of allene used for 8a-b and 8c, respectively; >98% conv. in all cases. See the Supporting Information for details.
Scheme 3
Scheme 3
Products from sequential catalytic allylcopper formation/addition to aryl ketones followed by C–B oxidation; >98% conv. in all cases. See Table 1 for conditions and the Supporting Information for experimental and analytical details.
Scheme 4
Scheme 4
Strategies involving initial preparation and use of 2-B(pin)-substituted allylboron reagents leads to alternative product isomers or demand the identification and use of a second catalyst, in contrast to the present Cu-catalyzed approach.
Scheme 5
Scheme 5
The Cu-catalyzed protocol can be used to obtain valuable vinylbromides with high efficiency.
Scheme 6
Scheme 6
Cu-catalyzed γ- and diastereoselective coupling of allenes with carbonyls can be performed enantioselectively through the use of chiral bis-phosphine ligands; >98% conv. in all cases. For exact conditions, see Table 1 and Scheme 5.
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References

    1. For a review on multi-component catalytic reactions, see: Touré BB, Hall DG. Chem. Rev. 2009;109:4439.

    1. For a relevant discussion, see: Bower JF, Kim IS, Patman RL, Krische MJ. Angew. Chem. Int. Ed. 2009;48:34. 2-Substituted allylmetal species cannot be accessed by Ir- and Ru-catalyzed reductive couplings with allenes, and there are no related processes involving ketones

    1. Yus M, González-Gómez JC, Foubelo F. Chem. Rev. 2011;111:7774. - PubMed

    1. See the Supporting Information for details.

    1. Jung B, Hoveyda AH. J. Am. Chem. Soc. 2012;134:1490. For a related study, see: Yuan W, Ma S. Adv. Synth. Catal. 2012;354:1867.

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