Synthesis and Application of Highly Substituted Cyclopentadienes

Densely substituted cyclopentadienes and pentafulvenes are important compounds because these compounds serve as versatile precursors of metallocenes that show high activity in valuable catalytic transformations. For example, half-sandwich metallocenes of late transition metals, such as rhodium, iridium, and cobalt, are highly active catalysts for the C–H bond functionalization. As the structural modification of cyclopentadienyl ligands on the metallocenes improves catalytic efficiency and selectivity, the development of new methods for the synthesis of substituted cyclopentadienes and pentafulvenes is highly important. In this chapter, the synthesis of highly substituted cyclopentadienes and pentafulvenes and their application to the synthesis of half-sandwich metallocenes of late transition metals are described.