Reaction of cyclopropylcarbene–metal complexes with nucleophiles, halogens and HX

The reaction of halogens, pseudohalogens, and HX with cyclopropyl(phenylthio)carbene-chromium complexes leads to the formation of 1,4-dihalo-1-thiophenyl-1-butene systems with a moderate-high degree of stereocontrol in the formation of the alkene. A mechanism involving electrophilic activation of the carbene complex followed by nucleophilic attack at the cyclopropane carbon has been proposed.