Background: Metathesis reactions represent an attractive and powerful tool for the synthesis of new carbon-carbon double bonds. The development of ruthenium complexes allows to perform the transformation in both organic and polymer chemistry. Indenylidene catalysts constitute a very important part of this area, as they have been found to be resistant to harsh reaction conditions (temperature and presence of functional groups). In addition, thanks to their good catalytic activities they quickly became a mainstream catalysts in metathesis-type reactions in recent years.
Objective: In this Review we intend to give a general overview of indenylidene catalysts in a broad sense.
Conclusion: Synthesis and activity studies of modified first- and second-generation complexes as well as catalysts bearing pyridine or bidenate ligands are described herein. The application of indenylidene catalysts is discussed in light of both simple model reactions and synthesis of biologically active compounds.