Stereospecific Insertion of the Carbene Ligand of a Fischer Carbene Complex into Olefinic CH Bonds

The C(OMe)Ph ligand of 1 is inserted into the β-C-H bond of (E)- and (Z)-2 with high stereoselectivity and with inversion of the olefin configuration (3). In cyclohexane at 80°C, this is the main reaction, and not, as expected, the formation of cyclopropanes. The experimental findings suggest a formation of 3 via metallacyclobutanes, β-Syn -elimination, and reductive elimination.