Synthesis of 1,2-Disubstituted Cyclopentadienes and Their Application

Cyclopentadiene and its substituted congeners have played an important role in organic chemistry since their discovery. Cyclopentadienyl and substituted cyclopentadienyl anions constitute currently a very important class of ligands for transition metal compounds. Cyclopentadienyl ligands in the respective metallocene complexes show usually high chemical inertness and stability. This property makes the metallocenes popular and indispensable catalysts in a plethora of organic transformations. This review focuses on development of synthetic pathways for preparation of selectively 1,2-disubstituted cyclopentadienes and their conversion to a wide variety of metallocenes. Application of 1,2-disubstituted metallocenes in catalytic processes is mentioned as well.