Résumé
Molecular ruthenium catalysts are now currently used to perform selective carbon– carbon bond formation by combination of simple substrates. Their tolerance toward functional groups has allowed the access to high value,multifunctional molecules. It will be shown that ruthenium catalysts allow the coupling of functional alkenes or alkynes with a variety of unsaturated molecules such as alkenes, dienes, alkynes, and diynes. A large range of electron-rich ruthenium or hydridoruthenium complexes are currently used for the formation of cyclic and polycyclic compounds on reaction with substrates containing several unsaturated C–C bonds. Ruthenium complexes have promoted several original activation pathways, such as C–H bond activation, the distribution of carbene from diazoalkanes, and especially their versatility in making a large variety of ruthenacycle intermediates. Besides the applications of ruthenium precatalysts in organic synthesis an important discussion of and mechanisms will be presented.