This communication describes a new and highly practical Pd(II)-catalyzed method for the regio- and chemoselective oxidative functionalization of arenes and alkanes. Carbon-hydrogen bonds of substrates that contain a variety of directing groups (e.g., pyridine, azobenzene, pyrazole, and imine derivatives) are selectively transformed into esters, ethers, and aryl-halides under mild conditions. The scope of this reaction in terms of substrate, directing group, and oxidant is described, and a preliminary catalytic cycle is proposed.
This communication describes the development of a new Pd-catalyzed method for the fluorination of carbon-hydrogen bonds. A key step of these transformations involves palladium-mediated carbon-fluorine coupling-a much sought after, but previously unprecedented, transformation. These reactions were successfully achieved under oxidative conditions using electrophilic N-fluoropyridinium reagents. Microwave irradiation in the presence of catalytic palladium acetate served as optimal conditions for the fluorination of C-H bonds in a variety of substituted 2-arylpyridine and 8-methylquinoline derivatives.
This communication describes a new palladium-catalyzed method for the oxygenation of unactivated sp3 C-H bonds. A wide variety of alkane substrates containing readily available oxime and/or pyridine directing groups are oxidized with extremely high levels of chemo-, regio-, and in some cases diastereoselectivity. The substrate scope of these reactions is discussed, and the high selectivities are rationalized on the basis of the requirements of putative palladium alkyl intermediates.
A modification of the Sonogoshira coupling reaction employing an amidine base and a substoichiometric amount of water generates symmetrical and unsymmetrical bisarylethynylenes in one pot through in situ deprotection of trimethylsilylethynylene-added intermediates.
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