Organocerium: A New Contender for Halogen-Metal Exchanges

In the context of our current research on dependable and sustainable methods for C-C bond-forming reactions, we have recently developed new strategies to generate organocerium reagents through simple bromide-cerium exchanges. n -Bu (3) Ce enabled a fast and general access to functionalized triaryl- and alkenyl cerium species from the corresponding aryl- and alkenyl bromides. A broad range of these new organocerium species was engaged in Zweifel's olefination, allowing for the synthesis of widely substituted alkene derivatives in a stereospecific way. Herein, we place the formation of organocerium species in the context of known organometallic reagents (Li, Mg, Zn, Cu, Ca, La, and Sm) generated through halogen-metal exchange reactions and their application in further transformations.