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. 2012 Nov 26;31(22):7823-7826.
doi: 10.1021/om300790t. Epub 2012 Sep 19.

NHC-Cu-Catalyzed Silyl Conjugate Additions to Acyclic and Cyclic Dienones and Dienoates. Efficient Site-, Diastereo- and Enantioselective Synthesis of Carbonyl-Containing Allylsilanes

Kang-Sang Lee  1 , Hao Wu, Fredrik Haeffner, Amir H Hoveyda
Affiliations

NHC-Cu-Catalyzed Silyl Conjugate Additions to Acyclic and Cyclic Dienones and Dienoates. Efficient Site-, Diastereo- and Enantioselective Synthesis of Carbonyl-Containing Allylsilanes

Kang-Sang Lee et al. Organometallics. .

Abstract

Efficient and highly diastereo- and enantioselective conjugate additions of phenyldimethylsilyl units to acyclic and cyclic dienones and dienoates are disclosed. The C-Si bond forming reactions are catalyzed by 2.0-2.5 mol % of a copper complex of a chiral monodentate N-heterocyclic carbene; the requisite reagent, PhMe(2)Si-B(pin), is commercially available or can be easily prepared. Transformations generate allylsilanes in up to 98% yield and >99:1 enantiomeric ratio, and proceed with complete 1,4-selectivity, unless the dienone or dienoate carries a trisubstituted alkene conjugated to the carbonyl group; in the latter cases, 1,6-addition products are obtained exclusively and in up to >98% Z selectivity.

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Figures

Figure 1
Figure 1. Proposed model for NHC-Cu-catalyzed enantioselective silyl conjugate additions
Scheme 1
Scheme 1. Enantioselective Synthesis of Carbonyl-Containing Allylsilanes by NHC–Cu-Catalyzed Silyl Conjugate Addition
Scheme 2
Scheme 2. Enantiomerically Enriched Acyclic Carbonyl-Containing Allylsilanesa
See this image and copyright information in PMC

References

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