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. 2010 Aug 11;132(31):10630-3.
doi: 10.1021/ja104777u.

Enantioselective synthesis of boron-substituted quaternary carbons by NHC-Cu-catalyzed boronate conjugate additions to unsaturated carboxylic esters, ketones, or thioesters

Jeannette M O'Brien  1 , Kang-sang Lee, Amir H Hoveyda
Affiliations

Enantioselective synthesis of boron-substituted quaternary carbons by NHC-Cu-catalyzed boronate conjugate additions to unsaturated carboxylic esters, ketones, or thioesters

Jeannette M O'Brien et al. J Am Chem Soc. .

Abstract

A Cu-catalyzed method for enantioselective boronate conjugate additions to trisubstituted alkenes of acyclic alpha,beta-unsaturated carboxylic esters, ketones, and thioesters is disclosed. All transformations are promoted by 5 mol % of a chiral monodentate NHC-Cu complex, derived from a readily available C(1)-symmetric imidazolinium salt, and in the presence of commercially available bis(pinacolato)diboron. Reactions are efficient (typically, 60% to >98% yield after purification) and deliver the desired beta-boryl carbonyls in up to >98:2 enantiomer ratio (er). Processes involving unsaturated thioesters proceed with higher enantioselectivity (vs carboxylic esters or ketones), and the resulting products can be functionalized by Ag-mediated or Pd-catalyzed reactions that furnish the derived carboxylic ester or various ketones. Routine oxidation affords beta-hydroxy ketones or carboxylic esters, ketone aldol products that cannot be otherwise prepared efficiently by an alternative catalytic enantioselective protocol.

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Figures

Scheme 1
Scheme 1
B-Substituted Quaternary Centers by Cu-Catalyzed Conjugate Additions
Scheme 2
Scheme 2
Cu–NHC-Catalyzed Enantioselective Boronate Conjugate Additions to Alkyl-Substituted α,β-Unsaturated Estersa
Scheme 3
Scheme 3
Cu–NHC-Catalyzed Enantioselective Boronate Conjugate Additions to an α,β-Unsaturated Ketonesa
Scheme 4
Scheme 4
Cu–NHC-Catalyzed Enantioselective Boronate Conjugate Additions to an α,β-Unsaturated Thioestersa
Scheme 5
Scheme 5
Conversion of β-Boryl Thioesters to Esters and Ketonesa
Figure 1
Figure 1
Proposed models for NHC–Cu-catalyzed boronate conjugate additions.
See this image and copyright information in PMC

References

    1. For Cu-catalyzed enantioselective boronate conjugate additions to unsaturated carbonyls with a disubstituted alkene, see: Lee J-E, Yun J. Angew. Chem., Int. Ed. 2008;47:145.Lillo V, Prieto A, Bonet A, Díaz-Requejo MM, Ramírez J, Pérez PJ, Fernández E. Organometallics. 2009;28:659.Sim H-S, Feng X, Yun J. Chem. Eur. J. 2009;15:1939.

    1. Jerphagnon T, Pizzuti MG, Minnaard AJ, Feringa BL. Chem. Soc. Rev. 2009;38:1039. - PubMed
    1. Wu J, Mampreian DM, Hoveyda AH. J. Am. Chem. Soc. 2005;127:4584. - PubMed

    1. For example, see: Wilsily A, Fillion E. J. Org. Chem. 2009;74:8583.

    1. Mauleón P, Carretero JC. Chem. Commun. 2005:4961. - PubMed

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