Perspective on dirhodium carboxamidates as catalysts.

Dirhodium compounds are emerging as highly efficient catalysts for diverse reactions, and those with carboxamidate ligands have the broadest applications. The unique features of these compounds are their structural rigidity, ease of ligand exchange, open diaxial sites for coordination with Lewis bases, and their low oxidation potential. As consequences of this, dirhodium carboxamidates are efficient and effective catalysts for metal carbene reactions, Lewis acid-catalyzed processes, and chemical oxidations. With chiral carboxamidate ligands these dirhodium compounds show exceptional enantiocontrol for intramolecular cyclopropanation and carbon-hydrogen insertion reactions of diazoacetates, and they are also highly efficient and selective for hetero-Diels-Alder reactions. Their limitations lie in their moderate reactivities for metal carbene generation and Lewis acid catalysis and in the cost of the precious metal rhodium.