Ruthenium-Induced Alkyne Cycloisomerization: Construction of Metalated Heterocycles,Revelation of Unconventional Reaction Pathways,and Exploration of Functional Applications

While the fascinating chemistry demonstrated by metalated N-heterocyclic carbene (NHC) complexes highlights the significance of metalated heterocyclic chemistry, the development of other metalated heterocycles is falling behind, presumably because of the sparseness of general synthetic methodologies. In this Concept article, the strategy to prepare metalated heterocyclic complexes by metal-induced cycloisomerization of heteroatom-functionalized alkynes is presented. The isolation of and calculations on novel ruthenium complexes bearing chromene, chromone, indole, indoline, indolizine, and indolizinone moieties prepared from reactions between alkynes and ruthenium complexes are discussed, with emphasis on the mechanistic insights into the ruthenium-induced alkyne transformations and applications in material design and drug discovery.