Copper-Catalyzed Decarboxylative Difluoroalkylation and Perfluoroalkylation of α,β-Unsaturated Carboxylic Acids

Photoinduced Decarboxylative Difluoroalkylation and Perfluoroalkylation of α-Fluoroacrylic Acids

Herein, a novel and practical methodology for the photoinduced decarboxylative difluoroalkylation and perfluoroalkylation of α-fluoroacrylic acids is reported. A wide range of α-fluoroacrylic acids can be used as applicable feedstocks, allowing for rapid access to structurally important difluoroalkylated and polyfluoroalkylated monofluoroalkenes with high Z-stereoselectivity under mild conditions. The protocol demonstrates excellent functional group compatibility and provides a platform for modifying complex biologically active molecules.

Cobalt-catalyzed decarboxylative difluoroalkylation of nitrophenylacetic acid salts

The selective installation of fluorine-containing groups into biologically relevant molecules has been used as a common strategy for the development of pharmaceutically active molecules. However, the selective incorporation of gem-difluoromethylene groups next to sterically demanding secondary and tertiary alkyl groups remains a challenge. Herein, we report the first cobalt-catalyzed regioselective difluoroalkylation of carboxylic acid salts. The reaction allows for the facile construction of various difluoroalkylated products in good yields tolerating a wide range of functionalities on either reaction partner. The potential of the method is illustrated by the late-stage functionalization of molecules of biological relevance. Mechanistic studies support the in situ formation of a cobalt(i) species and the intermediacy of difluoroalkyl radicals, thus suggesting a Co(i)/Co(ii)/Co(iii) catalytic cycle.

Development of Electrophilic Radical Perfluoroalkylation of Electron-Deficient Olefins

Fluorinated organic compounds have attracted significant attention over the past few decades owing to their unique properties and versatility. An established method for the synthesis of fluorinated organic compounds involves radical perfluoroalkylation reactions towards double bonds. In this radical pathway, electrophilic perfluoroalkyl radicals exhibit excellent reactivity towards electron-rich olefins. Therefore, several splendid perfluoroalkylation reactions of electron-rich olefins have been reported. However, there are only a few examples of reaction involving electron-deficient olefins because of their poor electronic compatibility with perfluoroalkyl radicals. This review focuses on the reports that challenge this long-standing issue. Radical perfluoroalkylation/bifunctionalization reactions of electron-deficient olefins are described according to the radical generation methods.

Visible-Light-Induced Metal-Free Decarboxylative Perfluoroalkylation of Aryl Acrylic Acids

Perfluoroalkylation is important for late-stage modification of biologically active molecules. Herein, we report a protocol for visible-light-induced perfluoroalkylation reactions of aryl acrylic acids. These reactions, which use perfluoroalkyl iodides as radical precursors and inexpensive eosin Y as a photocatalyst, proceed in a decarboxylative manner. The easy accessibility of perfluoroalkyl iodides and the broad substrate scope, mild conditions, and metal-free catalyst make this protocol applicable for the transformation of inexpensive raw materials to high-value chemicals.

Wonderful fusion of organofluorine chemistry and decarboxylation strategy

Decarboxylation strategy has been emerging as a powerful tool for the synthesis of fluorine-containing organic compounds that play important roles in various fields such as pharmaceuticals, agrochemicals, and materials science. Considerable progress in decarboxylation has been made over the past decade towards the construction of diverse valuable fluorinated fine chemicals for which the fluorinated part can be brought in two ways. The first way is described as the reaction of non-fluorinated carboxylic acids (and their derivatives) with fluorinating reagents, as well as fluorine-containing building blocks. The second way is dedicated to the exploration and the use of fluorine-containing carboxylic acids (and their derivatives) in decarboxylative transformations. This review aims to provide a comprehensive summary of the development and applications of decarboxylative radical, nucleophilic and cross-coupling strategies in organofluorine chemistry.

Ligand Promoted Olefination of Anilides for Indirectly Introducing Fluorinated Functional Groups via Palladium Catalyst

We report a palladium-catalyzed, ligand promoted, C-H fluorine-containing olefination of anilides with 4-bromo-3,3,4,4-tetrafluorobutene as the fluorinated reagent, which has a potential transformation into other compounds due to its -CF₂CF₂Br functional group. -CF₂CF₂H was obtained by using the mild reducing agent sodium borohydride. Bioactive compounds such as aminoglutethimide derivative and propham were well-tolerated in this reaction, both of which highlight the synthetic importance of this method.

Stereoselective synthesis of fluoroalkylated (Z)-alkene via nickel-catalyzed and iron-mediated hydrofluoroalkylation of alkynes

An efficient nickel-catalyzed, iron-mediated hydrofluoroalkylation of alkynes with bromodifluoroacetate or perfluoroalkyl iodide, which proceeded smoothly to give fluoroalkylated (Z)-alkenes with high stereocontrol (up to 99 : 1 Z/E), was developed.

Towards a practical perfluoroalkylation of (hetero)arenes with perfluoroalkyl bromides using cobalt nanocatalysts

This paper report a convenient methodology for perfluoroalkylation including trifluoromethylation of (hetero)arenes with perfluoroalkyl bromides using a specific cobalt-based nanocatalyst.

Synthesis of gem-Difluoromethylene Containing Cycloalkenes via the Ring-Opening Reaction of gem-Difluorocyclopropanes and Subsequent RCM Reaction

The radical-type ring-opening reaction of gem-difluorocyclopropanes and subsequent regioselective monoepoxidation of the products were demonstrated. Introduction of a vinyl or allyl group to the epoxide produced the diene derivatives that were subjected to the ring closing metathesis reaction to furnish the gem-difluoromethylene containing cyclopentene, cycloheptene, and cyclooctene derivatives in good to excellent yields.

Fluoroalkenylation of boronic acids via an oxidative Heck reaction

A fluoroalkenylation of boronic acids with fluoroalkyl alkenes has been developed. The Pd-catalyzed oxidative Heck coupling reaction proceeds under an oxygen atmosphere at room temperature, in the absence of a base and/or a ligand, showing excellent practicality of the process. This simple transformation is highly stereoselective to provide only E-isomers. In addition to the general approach using alkenes with functionalized fluoroalkyl reagents, this method, by transferring an aromatic system to the electron-deficient fluoroalkyl alkene, provides an efficient alternative method to yield valuable organofluorines.

Copper-mediated cascade radical cyclization of olefins with naphthalenyl iododifluoromethyl ketones

Copper-mediated radical cyclization of naphthalenyl iododifluoromethyl ketones with olefins was developed to generate a series of unprecedented gem-difluorodihydrophenanthrenones with excellent regioselectivity.

Synthesis of 2,2-difluoro-homoallylic alcohols via ring-opening of gem-difluorocyclopropane and aerobic oxidation by photo-irradiation in the presence of an organic pigment

The aerobic oxidation took place after the visible light-mediated ring-opening reaction of gem-difluorocyclopropane in the presence of an organic dye and amine to furnish 2,2-difluoro-homoallylic alcohols in good yields.

Copper-catalyzed remote oxidation of alcohols initiated by radical difluoroalkylation of alkenes: facile access to difluoroalkylated carbonyl compounds

A Cu-catalyzed oxidation of alcohols triggered by the radical difluoroalkylation of alkenes has been developed.

Regio- and Stereoselective Radical Perfluoroalkyltriflation of Alkynes Using Phenyl(perfluoroalkyl)iodonium Triflates

A method for regio- and stereoselective anti-addition of the perfluoroalkyl and the triflate group of phenyl(perfluoroalkyl)iodonium triflates to alkynes is presented. The radical reaction uses cheap CuCl as a smart initiator and can be conducted in gram scale. The perfluoroalkyltriflated products are readily further functionalized, rendering this transformation valuable.

Copper-catalyzed fluoroalkylation of alkynes, and alkynyl & vinyl carboxylic acids with fluoroalkyl halides

Copper-catalyzed fluoroalkylation of alkynes and alkynyl carboxylic acids has been achieved with high functional-group tolerance and excellent regio- and stereoselectivities.