Stereospecific Olefin Synthesis via Lithium Vinylcuprates

The conjugate addition of cis ‐ or trans ‐1‐alkenyl‐cuprolithium complexes (RCHCH) 2 CuLi · X n R  alkyl, X  ligands such as ether, tetrahydrofuran, (CH 3 O) 3 P and ( n ‐Bu) 3 P. Physical studies to determine the structure of these copper reagents are in progress, see footnote 20 of reference [1]. to α, β‐unsaturated carbonyl compounds was found to occur with high retention of double bond geometry, affording isomerically pure cis ‐ or trans ‐γ, δ‐ethylenic carbonyl compounds. The same 1‐alkenylcuprates also react stereospecifically with alkyl halides to give isomerically pure cis ‐ or trans ‐olefins.