Free-Amine Directed Arylation of Biaryl-2-amines with Aryl Iodides by Palladium Catalysis

A new palladium-catalyzed free-amine directed arylation of C(sp²)–H bonds in the presence of AgOAc and TFA is described. Biaryl-2-amines react with various aryl iodides to give the corresponding mono- or diarylated products with exclusive regioselectivity

Cu(II)-Promoted Palladium-Catalyzed C–H Ortho-Arylation of <i>N</i>,<i>N</i>‑Dimethylbenzylamines

A novel protocol for palladium-catalyzed arylation of the C­(sp²)–H bond directed by a <i>N</i>,<i>N</i>-dimethylaminomethyl group in the presence of AgOAc and Cu­(OAc)₂·H₂O is described. Various aryl iodides proved to be efficient coupling partners, furnishing the corresponding ortho monoarylated or diarylated arenes in moderate to good yields. Cu­(OAc)₂·H₂O is found to be the important additive to improve the yields in this transformation

Selective Synthesis of Alkynylated Isoquinolines and Biisoquinolines via Rh^III Catalyzed C–H Activation/1,3-Diyne Strategy

Described herein is a convenient and highly selective synthesis of alkynylated isoquinolines and biisoquinolines from various aryl ketone <i>O</i>-pivaloyloxime derivatives and 1,3-diynes via rhodium-catalyzed C–H bond activation. In this transformations, alkynylated isoquinolines, 3,4′- and 3,3′-biisoquinolines could be obtained respectively through changing the reaction conditions. Mechanistic investigation revealed that the C–H activation of aryl ketone <i>O</i>-pivaloyloxime was the key step to this reaction

Encaging Palladium Nanoparticles in Chitosan Modified Montmorillonite for Efficient, Recyclable Catalysts

Metal nanoparticles, once supported by a suitable scaffolding material, can be used as highly efficient heterogeneous catalysts for numerous organic reactions. The challenge, though, is to mitigate the continuous loss of metals from the supporting materials as reactions proceed, so that the catalysts can be recycled multiple times. Herein, we combine the excellent chelating property of chitosan (CS) and remarkable stability of montmorillonite (MMT) into a composite material to support metal catalysts such as palladium (Pd). The in situ reduction of Pd²⁺ into Pd⁰ in the interstices of MMT/CS composites effectively encages the Pd⁰ nanoparticles in the porous matrices, while still allowing for reactant and product molecules of relatively small sizes to diffuse in and out the matrices. The prepared Pd⁰@MMT/CS catalysts are highly active for the Heck reactions of aromatic halides and alkenes, and can be recycled 30 times without significant loss of activities. Positron annihilation lifetime analysis and other structural characterization methods are implemented to elucidate the unique compartmentalization of metal catalysts in the composite matrices. As both CS and MMT are economical and abundant materials in nature, this approach may facilitate a versatile platform for developing highly recyclable, heterogeneous catalysts containing metal nanoparticles