Abstract
It has been known since the 1990s that the introduction of a ferrocenyl-type substituent into compounds with proven biological activity can improve their properties. More recently, it was also shown that a carbon bridge connecting the two cyclopentadienyl rings in ferrocene derivatives could enhance the biological properties of the new compounds compared to those without them. However, the synthesis of ferrocenes with this additional linker, known as ansa-ferrocenes, is more difficult due to advanced synthetic protocols and the phenomenon of planar chirality in ring-substituted compounds. As a result, research into the formation of hybrids, conjugates and other ansa-ferrocene derivatives has not been widely conducted. This review discusses the potential biological properties of these units, covering scientific articles published between 1980 and 2024.