Cyclopentadienyl complexes of group 9 metals in the total synthesis of natural products

Organic transformations catalyzed by cyclopentadienyl complexes of Group 9 metals (cobalt, rhodium and iridium) are the key steps of the total synthesis of various natural products. These complexes efficiently catalyze [2 + 2 + 2] cycloaddition, asymmetric transfer hydrogenation, C–H activation reactions, including annulation, alkylation, olefination and amidation processes. The advantages and drawbacks of these transformations, as well as the reaction mechanisms, are discussed. The review is comprehensive and summarizes the information on the use of cyclopentadienyl complexes of Group 9 metals in the total synthesis of natural compounds, published in the literature up to 2021.