The area of transition-metal-catalyzed direct arylation through cleavage of CH bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners—including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations

Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage.

Catalysis for the valorization of exhaust carbon: from CO2 to chemicals, materials, and fuels. technological use of CO2.

Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo- and transition-metal catalysis. The most challenging transformation remains the formation of the parent C-F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal-fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost-efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.

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Introduction of Fluorine and Fluorine-Containing Functional Groups

Direct C-H transformation via iron catalysis.

Recent advances in catalysis have made the incorporation of fluorine into complex organic molecules easier than ever before, but selective, general and practical fluorination reactions remain sought after. Fluorination of molecules often imparts desirable properties, such as metabolic and thermal stability, and fluorinated molecules are therefore frequently used as pharmaceuticals or materials. But the formation of carbon-fluorine bonds in complex molecules is a significant challenge. Here we discuss reactions to make organofluorides that have emerged within the past few years and which exemplify how to overcome some of the intricate challenges associated with fluorination.

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Catalysis for fluorination and trifluoromethylation

We present a safe and convenient cross-coupling strategy for the large-scale synthesis of biaryls, commercially important structures often found in biologically active molecules. In contrast to traditional cross-couplings, which require the prior preparation of organometallic reagents, we use a copper catalyst to generate the carbon nucleophiles in situ, via decarboxylation of easily accessible arylcarboxylic acid salts. The scope and potential economic impact of the reaction are demonstrated by the synthesis of 26 biaryls, one of which is an intermediate in the large-scale production of the agricultural fungicide Boscalid.

http://science.sciencemag.org/content/sci/313/5787/662.full.pdf

Synthesis of Biaryls via Catalytic Decarboxylative Coupling

Late transition metal-catalyzed hydroamination and hydroamidation.

This tutorial review provides a comparison between the concepts of catalytic decarboxylative and decarbonylative couplings for the ipso-substitution of carboxylate groups, and illustrates their potential benefits over alternative C–C bond-forming reactions. Redox-neutral decarboxylative reactions allow generating organometallic species with nucleophilic reactivity via the extrusion of carbon dioxide from metal carboxylates. Such C–C bond activating processes provide a way of employing carboxylate salts as substitutes for the traditional sources of carbon nucleophiles, i.e. stoichiometric organometallic reagents. If the decarboxylation of carboxylic acids is performed under oxidative conditions, organometallic species with electrophilic reactivity are obtained instead. These can alternatively be accessed via the extrusion of carbon monoxide from acyl–metal species generated via the oxidative addition of activated carboxylic acid derivatives (e.g. acid chlorides, anhydrides or esters) to metal complexes. In the latter two reaction types, carboxylic acids thus become substitutes for organohalides. The complementary redox-neutral and oxidative decarboxylative and decarbonylative reaction modes allow the broad use of carboxylic acids as substrates in C–C bond-forming reactions. Their applicability, scope and limitations are discussed using the examples of Heck reactions, cross-couplings and direct arylations.

Carboxylates as sources of carbon nucleophiles and electrophiles: comparison of decarboxylative and decarbonylative pathways

Carbonsäuren als Substrate in der homogenen Katalyse

Potassium (trifluoromethyl)trimethoxyborate is introduced as a new source of CF(3) nucleophiles in copper-catalyzed trifluoromethylation reactions. The crystalline salt is stable on storage, easy to handle, and can be obtained in near-quantitative yields simply by mixing B(OMe)(3), CF(3)SiMe(3), and KF. The trifluoromethylation reagent allows the conversion of various aryl iodides into the corresponding benzotrifluorides in high yields under mild, base-free conditions in the presence of catalytic quantities of a Cu(I)/1,10-phenanthroline complex.

Lukas J. Gooßen

Papers

Synthesis of Biaryls via Catalytic Decarboxylative Coupling

Late transition metal-catalyzed hydroamination and hydroamidation.

Carboxylates as sources of carbon nucleophiles and electrophiles: comparison of decarboxylative and decarbonylative pathways

Carbonsäuren als Substrate in der homogenen Katalyse

Copper‐Catalyzed Trifluoromethylation of Aryl Iodides with Potassium (Trifluoromethyl)trimethoxyborate