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Synlett 1994; 1994(4): 271-272
DOI: 10.1055/s-1994-22824
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Preparation of γ, δ-Unsaturated Acids via Conjugate Addition of RCu(LiI)-TMSI to Allylic α, β-Unsaturated Esters followed by Claisen Rearrangement

Magnus Eriksson* , Martin Nilsson, Thomas Olsson
  • *Department of Organic Chemistry, Chalmers University of Technology, S-412 96 GÖTEBORG, SWEDEN
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Publication Date:
22 March 2002 (online)

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Conjugate addition of monoorganocopper reagents and iodotrimethylsilane to allylic α, β-unsaturated esters proceeds well at -78 °C. The intermediate allylic silyl ketene acetals rearrange at room temperature to give good yields of diastereomeric γ, δ-unsaturated acids after aqueous work-up. Monoorganocopper reagents give mainly erythro form of the acids. Lithium diorganocuprates together with TMSCI give conjugate addition to acrylates to afford mainly threo form of the acid after rearrangement and work-up. Less reactive esters give mixtures of conjugate addition and SN2 alkylation products.