Cobalt‐Catalyzed Isomerization of 1‐Alkenes to (E)‐2‐Alkenes with Dimethylphenylsilylmethylmagnesium Chloride and Its Application to the Stereoselective Synthesis of (E)‐Alkenylsilanes

Treatment of 1-alkenes with dimethylphenylsilylmethylmagnesium chloride in the presence of a cobalt-NHC complex in dioxane at 50 degrees C or higher provides the corresponding (E)-2-alkenes selectively. The isomerization is applicable to the stereoselective synthesis of (E)-crotylsilanes and (E)-1-propenylsilanes from the corresponding homoallylsilanes and allylsilanes, respectively.