The Stereoselective Addition of a Gilman Reagent to an α,ß-Unsaturated Ester
Dr. Jeffrey Johnson, Hope College
The addition of a Gilman reagent to an α,ß-unsaturated ester is normally a non stereoselective process. When a methyl substituted Gilman reagent reacts with an α,ß-unsaturated ester it adds to either face of the alkene, giving two enantiomers. In the reaction reported by Kuwahara (J. Org. Chem. 2008, 73, 6913-6915) the addition of a Gilman reagent to an α,ß-unsaturated ester with a pendant alkene showed a complete stereoselectivity that Kuwahara explains using the Felkin-Anh Model. The complete stereoselectivity is unusual for Felkin-Anh, suggesting that other factors are involved such as an intermediate where the copper ion of the Gilman reagent complexes with the two alkenes. To test this hypothesis we have synthesized a saturated analog of the precedent compound for comparison of stereoselectivities in the Gilman reaction.
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