New Catalytic Performances of Ruthenium and Rhodium Complexes Directed toward Organic Synthesis with High Atom Efficiency

Low-valent ruthenium complexes often show intriguing and characteristic catalytic activity for novel organic transformations with high atom efficiency. The design and synthesis of novel low-valent ruthenium complexes having a variety of electron-donating and/or electron-withdrawing ligands is most promising strategy. Several ruthenium catalysts achieved the construction of novel functional organic molecules through cleavage of carbon–carbon single bonds, cocyclization of alkynes, alkenes, and/or carbon monoxide, and co-oligomerization of different alkenes without formation of by-products, which meets green and sustainable requirements for organic synthesis in the 21st century. Note that many findings in ruthenium catalysis have opened the door to a new field of rhodium-catalyzed synthetic organic chemistry, represented by cocyclization of alkynes and heterocumulenes.