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.

Base/B2pin2-Mediated Iodofluoroalkylation of Alkynes and Alkenes

A base/B2pin2-mediated iodofluoroalkylation of alkynes and a part of alkenes, using ethyl difluoroiodoacetate (ICF2CO2Et) or ICnF2n+1 (n = 3, 4, 6) as difluoroacetylating or perfluoroalkylating reagent, is disclosed. The reaction proceeds under mild conditions, and iododifluoroalkylation, hydrodifluoroalkylation and several perfluoroalkylation products were generated from alkynes or alkenes. Notably, this methodology provides a simple access to difluoroalkylated and perfluoroalkylated organic compounds starting from simple alkynes or alkenes.

Co-Catalyzed atom transfer radical addition of bromodifluoroacetamides, expanding the scope of radical difluoroalkylation

The atom transfer radical addition (ATRA) of bromodifluoroacetamides to arylalkynes and terminal alkenes was conducted using von Wangelin's Co catalyst system (CoBr₂/1,2-bis(diphenylphosphino)benzene/Zn) in acetone/H₂O at 30 °C to afford the corresponding functionalized difluoroacetamides in 33-89% yields. Moreover, the Co catalyst was successfully applied to the tandem addition/cyclization of 1,6-diene and -enyne substrates and intramolecular ATRA of N-allyl and N-propargyl bromodifluoroacetamides, significantly expanding the scope of radical difluoroalkylation.

Copper-catalyzed switchable cyclization of alkyne-tethered α-bromocarbonyls: selective access to quinolin-2-ones and quinoline-2,4-diones

Copper-catalyzed cyclization of alkynes has played a significant role in modern catalytic chemistry.

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.

Visible light photocatalytic cross-coupling and addition reactions of arylalkynes with perfluoroalkyl iodides

Visible light photocatalytic cross-coupling and addition reactions of arylalkynes with perfluoroalkyl iodides have been developed. Through slight modifications of the reaction conditions, reactions that are selective for the preparation of the C-C coupling product (perfluoroalkyl alkynes) and the addition products (iodo-perfluoroalkyl substituted alkenes) can be achieved. These reactions work well with different types of alkynes and perfluoroalkyl iodides. As the iodide generated from the reaction can serve as a reductant to regenerate the photocatalyst from its oxidized form, no sacrificial electron donor is required.

Metal-Free Iodoperfluoroalkylation: Photocatalysis versus Frustrated Lewis Pair Catalysis

A comparison of two catalytic, metal-free iodoperfluoro­alkylation protocols is presented. Frustrated Lewis pairs [ t Bu3P/B(C6F5)3] or phosphines/phosphites under visible light irradiation efficiently mediate the functionalization of non-activated alkenes and alkynes. A comprehensive account of the corresponding substrate scopes as well as insights into the mechanistic details of both reaction pathways are provided.

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.

Synthesis of tri-substituted allyl alcohols via a copper/iron co-catalyzed cascade perfluoroalkylation/rearrangement of aryl propynyl ethers

A copper/iron co-catalyzed fluoroalkylation of aryl propynyl ethers for the synthesis of perfluoroalkylated tri-substituted allyl alcohol derivatives is reported.

Copper-mediated regioselective hydrodifluoroalkylation of alkynes

A highly regioselective copper-mediated hydrodifluoroalkylation of alkynes with ethyl bromodifluoroacetate or bromodifluoroacetamides has been developed.

Copper-catalyzed three-component cyclization of amidines, styrenes, and fluoroalkyl halides for the synthesis of modular fluoroalkylated pyrimidines

An efficient copper-catalyzed three-component cyclization for the construction of highly functionalized pyrimidine derivatives from amidines, styrenes and fluoroalkyl halides is developed.

Recent advances in radical transformations of internal alkynes

This review highlights the recent progress in the radical transformation of internal alkynes and focuses on the reaction mechanisms by carbon/heteroatom-centered triggered additions, and offers a comprehensive overview on the existing procedures and employed methodologies.

Phosphinodifluoroalkylation of alkynes using P(O)H compounds and ethyl difluoroiodoacetate

The first phosphinodifluoroalkylation of alkynes is achieved and the simultaneous addition of both difluoromethylene and phosphinoyl groups across the alkynes with high regio- and stereoselectivity is of great significance.