Catalytic dehalogenation of sp2 C-F and C-Cl bonds in fluoro- and chloroalkenes

Catalytic dehalogenation of fluorinated and chlorinated ethylenes by (PPh3)(3)RhCl in the presence of Et3SiH at 35 degrees C is described, and product identity and kinetic parameters were determined. This system has an intramolecular preference for Cl over F removal, an intermolecular preference for F- over Cl-containing alkenes, and a strong preference for sp(2) over sp(3) carbon-halogen bonds. Both the substitution pattern and the substituent identity are important in determining the rate of the dehalogenation.