Ruthenium-Catalyzed Reactions-A Treasure Trove of Atom-Economic Transformations

The demand for new chemicals spanning the fields of health care to materials science combined with the pressure to produce these substances in an environmentally benign fashion pose great challenges to the synthetic chemical community. The maximization of synthetic efficiency by the conversion of simple building blocks into complex targets remains a fundamental goal. In this context, ruthenium complexes catalyze a number of non‐metathesis conversions and allow the rapid assembly of complex molecules with high selectivity and atom economy. These complexes often exhibit unusual reactivity. Careful consideration of the mechanistic underpinnings of the transformations can lead to the design of new reactions and the discovery of new reactivity. Ru complexes emerged from obscurity to become accepted as ideal catalysts for diverse CC bond‐forming reactions beyond the more‐well‐known redox and metathesis processes. These reactions are highly selective and atom‐economic processes for the synthesis of complex molecules (see scheme). Mechanistic principles provide the basis for the semirational design of new reactions, notably for CC coupling.