Dirhodium: carbene transformations and beyond

Dirhodiums, which feature lantern- or paddlewheel-like structures, have emerged as a class of useful catalysts in organic synthesis. Among the transformations catalyzed by dirhodiums, the carbene, with diazo, cyclopropene, hydrazone and triazole as the precursors, and nitrene transfer reactions are dominant and have reached remarkable levels of efficiency and selectivity. Additionally, more and more fascinating properties of dirhodium have been explored and discovered in the past few decades, which has accelerated the applications of dirhodium in organic synthesis. In this review, we aim to showcase these advances in dirhodium-catalyzed transformations. The transformations including cycloisomerization, hetero-Diels-Alder (HDA) reactions, ene reactions, arylation, radical oxidation reactions and C-H activation, etc. will be covered. In these reactions, the dirhodiums could not only work as redox-neutral catalysts but also as redox catalysts.