Weinreb Amide Directed Versatile C-H Bond Functionalization under (η -Pentamethylcyclopentadienyl)cobalt(III) Catalysis.

The (η -pentamethylcyclopentadienyl)cobalt(III) (CpCo )-catalyzed C-H bond functionalization of aromatic, heteroaromatic, and α,β-unsaturated Weinreb amides was explored. C-H allylation reactions with the use of allyl carbonate and a perfluoroalkene, oxidative alkenylation reactions with the use of ethyl acrylate, iodination reactions with the use of N-iodosuccinimide, and amidation reactions with the use of dioxazolones were catalyzed by CpCo(CO)I in the presence of a cationic Ag salt and AgOAc to afford various synthetically useful building blocks. Mechanistic studies of the C-H allylation disclosed that the C-H activation step was rate determining and virtually irreversible.