Recent advances in the development of ruthenium catalysts for the atom transfer radical addition of polyhalogenated compounds to olefins (Kharasch reaction) are described. Three classes of homogeneous catalysts are discussed: halfsandwich complexes with η6-arene, η5-cyclopentadienyl or η5-carborane ligands, ruthenium complexes with alkylidene- or vinylidene ligands and polynuclear complexes. Furthermore, first attempts to use immobilized ruthenium complexes as heterogeneous catalysts for the Kharasch reaction are summarized.
Keywords: metathesis, N-heterocyclic carbenes (NHC), halfsandwich complexes, polyhalogenated compounds, olefins, anti-Markovnikov adduct