Cobalt-catalyzed mono-coupling of R_3SiCH_2MgCl with 1,2-dihalogenoethylene:a general route to gamma-substituted (E)-allylsilanes

摘要

The reaction of trimethylsilylmethylmagnesium chloride (TMSCH_2MgCl) with 1,2-dihalogenoethylene in the presence of 1 mol% of Co(II) or Co(III) acetylacetonate in THF or THF-NMP proceeded exclusively in a mono-coupling pathway to provide 3-trimethylsilyl-l-halogeno-l-propene with >99% of E geometry in high yield,which was converted to a variety of y-substituted allylsilanes by Ni-or Pd-catalyzed coupling with organometallic compounds.