Native Amide-Directed C(sp )-H Amidation Enabled by Electron-Deficient Rh Catalyst and Electron-Deficient 2-Pyridone Ligand.

Trivalent group-9 metal catalysts with a cyclopentadienyl-type ligand (CpM ; M=Co, Rh, Ir, Cp=cyclopentadienyl) have been widely used for directed C-H functionalizations, albeit that their application to challenging C(sp )-H functionalizations suffers from the limitations of the available directing groups. In this report, we describe directed C(sp )-H amidation reactions of simple amide substrates with a variety of substituents. The combination of an electron-deficient Cp Rh catalyst (Cp =1,3-bis(ethoxycarbonyl)-substituted Cp) and an electron-deficient 2-pyridone ligand is essential for high reactivity.

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

The (η -pentamethylcyclopentadienyl)cobalt(III) (Cp*Co )-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 Cp*Co(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.

Cp*Co(III)-Catalyzed Dehydrative C-H Allylation of 6-Arylpurines and Aromatic Amides Using Allyl Alcohols in Fluorinated Alcohols.

Cp*Co(III)-catalyzed C-H allylation of various aromatic C-H bonds using allyl alcohols as allylating reagents is described. Improved reaction conditions using fluorinated alcohol solvents afforded efficient directed C-H allylation of 6-arylpurines, benzamides, and a synthetically useful Weinreb amide with good functional group compatibility.