Editorial [Hot Topic: Ruthenium Catalyzed Processes (Guest Editor: Jose Gimeno)]

Applications of organo-ruthenium derivatives in homogeneous catalysis have disclosed one of the cornerstones in the spectacular development of Organometallic Chemistry during the last decade. The special ability of ruthenium complexes to form a wide range of inorganic and organometallic complexes, featuring a wide scope of oxidation states, several coordination geometries and reactivity patterns, has triggered a growing interest. Nowadays, they may be considered, in a wide number of chemical transformations, as very competitive alternatives to other classical transition metal catalysts such as palladium, rhodium, platinum etc. giving rise, indeed, to a very appealing field of research. The present issue of Current Organic Chemistry entitled "Ruthenium Catalyzed Processes" deals with a series of nine articles from expert authors in the field illustrating recent developments of the usefulness in organic synthesis. The articles show the state of the art of specific aspects as well as complement important issues not covered by recent reviews or monographs on their catalytic applications The contributions highlight the progress of the catalytic activity in novel C-C bond forming reactions including allylic activation (C. Bruneau and co-workers), propargylic alcohol substitutions, (Y. Nishibayashi and S. Uemura) and other type involving Lewis acid catalysis (J. Faller and J. Parr). In their article J. Gimeno and co-workers summarize the chemistry of bis-allyl ruthenium(IV) derivatives and their catalytic applications in, among other reactions, polymerization of olefins, transfer hydrogenation of ketones and isomerization of allylic alcohols in water. Two articles dealing with Ring-closing metathesis (D.E. Fogg and J.C. Conrad) and applications of novel N-heterocyclic carbene-ruthenium complexes (A.F. Noels and co-workers) give further details on the well-known catalytic applications of carbene ruthenium complexes. The catalytic activity of ruthenium complexes in reactions involving transfer of atoms through radical additions such as Kharash reactions (K. Severin) and asymmetric atom-transfer reactions (C. Bonaccorsi and A. Mezzetti), illustrates the ability to catalyze this relatively less studied type of processes. Finely, the article from K. Kaneda and co-workers reviews the catalytic activity of immobilized-ruthenium complexes showing the promising applications of heterogeneous ruthenium catalysts in the development of a sustainable chemistry. I thank all the authors for their valuable reviews which I hope will be helpful to many organic chemists interested in innovative and non-classical chemical transformations.