Selective homogeneous transfer hydrogenolysis of trihalomethyl compounds by alcohols and ruthenium-phosphine catalysts

Dichlorotris(triphenylphosphine)ruthenium(II) was shown to catalyze hydrogen transfer from halogen-free alcohols to α-trichloromethyl- and α-tribromomethyl carbinols and to give selectively dihalomethyl derivatives. Benzyl alcohols proved to be very efficient hydrogen donors. Aliphatic secondary carbinols reacted better than primary ones. The catalytic process was affected by the electronic structure of the catalyst and of the hydrogen acceptor but not by that of the hydrogen donor.