Visible-Light-Induced Hydrodifluoromethylation of Alkenes with a Bromodifluoromethylphosphonium Bromide

Preparation of Difluoromethylated Benzothiophene by Visible-Light-Mediated Alkyne Difunctionalization Reaction

An efficient method for the preparation of difluoromethylated benzothiophenes via visible-light-mediated alkyne difunctionalization was developed. In this method, inexpensive sodium difluoromethanesulfinate (HCF2SO2Na) was used as the fluorine source, and a variety of benzothiophene derivatives were obtained in moderate to excellent yield under mild reaction conditions. Moreover, the reaction operation is simple and easy to scale up.

A facile access to aliphatic trifluoromethyl ketones via photocatalyzed cross-coupling of bromotrifluoroacetone and alkenes

Biological molecules incorporating trifluoromethyl ketones (TFMKs) have emerged as reversible covalent inhibitors, aiding in the management and treatment of inflammatory diseases, cancer, and respiratory conditions. TFMKs, renowned for their versatile binding properties and adaptability, are pivotal in the rational design of novel drugs for diverse diseases. The photocatalytic insertion of alkenes, abundant feedstocks, into the α-carbon of trifluoromethylacetone represents a highly effective and atom-economical method for synthesizing valuable TFMKs. However, these processes typically necessitate high-energy photoirradiation (λ > 300 nm, Hg lamp) and stoichiometric oxidants to generate the acetonyl radical from acetone. In our study, we demonstrate the visible-light photocatalytic radical addition into olefins using bromotrifluoroacetone as the trifluoroacetonyl radical precursor under mild conditions. Aliphatic trifluoromethyl ketones or the corresponding bromo-substituted products can be obtained by selecting an appropriate photocatalyst and solvent. Comprehensive experimental investigations, including cyclic voltammetry, Stern-Volmer quenching studies, and kinetic isotope effects, corroborate the synthesis of trifluoroacetonyl radical species from bromotrifluoroacetone under photoredox conditions. Further, we demonstrate the efficient synthesis of an oseltamivir derivative bearing a trifluoromethylketone moiety, which shows promising biological activity. Hence, this methodology will streamline the direct introduction of trifluoromethyl ketone into biological target molecules during drug discovery.

Photocatalytic fluoroalkylation by ligand-to-metal charge transfer

Trifluoromethyl (CF3) and other fluoroalkyl groups are of great significance in the fields of pharmaceutical chemistry and agricultural chemicals. Fluoroalkyl acids, especially trifluoroacetic acid (TFA) is considered the most ideal fluoroalkylation reagent due to its low cost and easy availability. However, the extremely high oxidation potential requirement of TFA limits its wide application. In recent years, since visible-light-induced fluoroalkylation through the ligand-to-metal charge transfer (LMCT) process can overcome the above limitations, it has become an effective synthetic tool for the construction of fluorinated compounds with complex molecules and structures. In this review, according to the classification of different metal catalysts, we summarize the trifluoromethylation and fluoroalkylation of olefins, heteroaromatics, and terminal alkynes in different metal catalytic systems and their corresponding reaction mechanisms. The photocatalytic fluoroalkylation via LMCT is believed to expedite the development of fluoro-containing drugs, and more novel fluoroalkylation methologies using this strategy will be disclosed.

Photoredox-Catalysis Fluorosulfonyldifluoromethylation of Unactivated Alkenes and (Hetero)arenes with ICF2SO2F

The fluorosulfonyldifluoromethylation of unactivated alkenes and (hetero)arenes with iododifluoromethanesulfonyl fluoride (ICF2SO2F) under visible light photoredox catalysis was successfully developed. Key to the successful fluorosulfonyldifluoromethylation of aromatic compounds was the usage of AgOTf as an additive to promote the formation of the CF2SO2F radical. The protocol provided a straightforward way to introduce the interesting and useful CF2SO2F group on sp3 and sp2 carbons.

Cu-Electrocatalysis Enables Vicinal Bis(difluoromethylation) of Alkenes: Unraveling Dichotomous Role of Zn(CF2H)2(DMPU)2 as Both Radical and Anion Source

The difluoromethyl group (CF2H) serves as an essential bioisostere in drug discovery campaigns according to Lipinski's Rule of 5 due to its advantageous combination of lipophilicity and hydrogen bonding ability, thereby improving the ADME properties. However, despite the high prevalence and importance of vicinal hydrogen bond donors in pharmaceutical agents, a general synthetic method for doubly difluoromethylated compounds in the vicinal position is absent. Here we describe a copper-electrocatalyzed strategy that enables the vicinal bis(difluoromethylation) of alkenes. By leveraging electrochemistry to oxidize Zn(CF2H)2(DMPU)2-a conventionally utilized anionic transmetalating source, we paved a way to utilize it as a CF2H radical source to deliver the CF2H group in the terminal position of alkenes. Mechanistic studies revealed that the interception of the resultant secondary radical by a copper catalyst and subsequent reductive elimination is facilitated by invoking the Cu(III) intermediate, enabling the second installation of the CF2H group in the internal position. The utility of this electrocatalytic 1,2-bis(difluoromethylation) strategy has been highlighted through the late-stage bioisosteric replacement of pharmaceutical agents such as sotalol and dipivefrine.

Visible Light-Induced Radical Cascade Difluoromethylation/Cyclization of Unactivated Alkenes: Access to CF2H-Substituted Polycyclic Imidazoles

An efficient and mild protocol for the visible light-induced radical cascade difluoromethylation/cyclization of imidazoles with unactivated alkenes using easily accessible and bench-stable difluoromethyltriphenylphosphonium bromide as the precursor of the -CF2H group has been developed to afford CF2H-substituted polycyclic imidazoles in moderate to good yields. This strategy, along with the construction of Csp3-CF2H/C-C bonds, is distinguished by mild conditions, no requirement of additives, simple operation, and wide substrate scope. In addition, the mechanistic experiments have indicated that the difluoromethyl radical pathway is essential for the methodology.

The 18F-Difluoromethyl Group: Challenges, Impact and Outlook

The difluoromethyl functionality has proven useful in drug discovery, as it can modulate the properties of bioactive molecules. For PET imaging, this structural motif has been largely underexploited in (pre)clinical radiotracers due to a lack of user-friendly radiosynthetic routes. This Minireview provides an overview of the challenges facing radiochemists and summarises the efforts made to date to access 18F-difluoromethyl-containing radiotracers. Two distinct approaches have prevailed, the first of which relies on 18F-fluorination. A second approach consists of a 18F-difluoromethylation process, which uses 18F-labelled reagents capable of releasing key reactive intermediates such as the [18F]CF2H radical or [18F]difluorocarbene. Finally, we provide an outlook for future directions in the radiosynthesis of [18F]CF2H compounds and their application in tracer radiosynthesis.

Visible-Light-Induced Hydrodifluoromethylation of Unactivated Alkenes with Difluoroacetic Anhydride

We herein described a practical and efficient protocol for hydrodifluoromethylation of unactivated alkenes using readily available difluoroacetic anhydride as a difluoromethyl source by merging photocatalysis and N-hydroxyphthalimide activation. This method features a wide substrate scope and excellent compatibility with various functional groups, as demonstrated by more than 50 examples, including bioactive molecules and pharmaceutical derivatives. Mechanism investigation indicated that N-hydroxyphthalimide may also serve as the hydrogen atom donor.

Photoredox/copper-catalyzed gem-difluoroalkylation-cyanation of 1,3-enynes

A photoredox/copper-catalyzed 1,4-difunctionalization of 1,3-enynes with readily available difluoroalkylating reagents and TMSCN was developed. This reaction proceeded at mild conditions, affording the corresponding difluoroalkylated allenes in good yields with high functional-group tolerance and excellent regioselectivity.

Promoting Photocatalytic Direct C-H Difluoromethylation of Heterocycles using Synergistic Dual-Active-Centered Covalent Organic Frameworks

Difluoromethylation reactions are increasingly important for the creation of fluorine-containing heterocycles, which are core groups in a diverse range of biologically and pharmacologically active ingredients. Ideally, this typically challenging reaction could be performed photocatalytically under mild conditions. To achieve this separation of redox processes would be required for the efficient generation of difluoromethyl radicals and the reduction of oxygen. A covalent organic framework photocatalytic material was, therefore, designed with dual reactive centers. Here, anthracene was used as a reduction site and benzothiadiazole was used as an oxidation site, distributed in a tristyryl triazine framework. Efficient charge separation was ensured by the superior electron-donating and -accepting abilities of the dual centers, creating long-lived photogenerated electron-hole pairs. Photocatalytic difluoromethylation of 16 compounds with high yields and remarkable functional group tolerance was demonstrated; compounds included bioactive molecules such as xanthine and uracil. The structure-function relationship of the dual-active-center photocatalyst was investigated through electron spin resonance, femtosecond transient absorption spectroscopy, and density functional theory calculations.

Photoredox Catalyzed Radical Fluoroalkylation with Non-Classical Fluorinated Reagents

The emergence of photocatalysis has greatly advanced radical fluoroalkylation reactions. Central to this advancement is the introduction and refinement of radical reagents, which play a pivotal role in driving these reactions forward. Intriguingly, some of these reagents, previously not recognized for their radical properties, have emerged as key players in this area. In this Perspective, we provide an overview of four representative reagents pioneered by our laboratory, which have subsequently garnered extensive application in broader research contexts, including difluorocarbene precursors bromodifluoromethylphosphonium bromide, electrophilic sulfonylation reagent triflic anhydride, and nucleophilic trifluoromethylation reagent methyl fluorosulfonyldifluoroacetate (Chen's reagent). The integration of phosphonium reagents, triflic anhydride, and methyl fluorosulfonyldifluoroacetate into photocatalysis has enabled some unexpected reactivities and now notably expanded the capabilities in radical difluoromethylation, trifluoromethylation, and difluoroalkylation. Our discussion highlights how these atypical reagents have enriched the toolkit available for radical fluoroalkylations, offering insights that could inspire future research and application in this area.

Difluoromethylated Difunctionalization of Alkenes under Visible Light

Difluoromethylated compounds usually act as bioisosteres for alcohol functional groups and show unique physicochemical and biological properties. The cyano-difluoromethylation of alkenes using 5-((difluoromethyl)sulfonyl)-1-phenyl-1H-tetrazole as a CF2H radical difluoromethyl precursor was developed to afford nitriles including a CF2H group. A low-cost, stable, easily handled 5-((difluoromethyl)sulfonyl)-1-methyl-1H-tetrazole (DFSMT) was synthesized and applied as the radical CF2H reagent. Using DFSMT as the radical CF2H precursor, the oxyl-difluoromethylation of alkenes was developed to obtain difluoromethylated ether products. All of the reactions showed good functional group tolerability. Initial mechanistic experiments indicated that the CF2H radical was involved as the key active intermediate.

Difluoromethylation-Carboxylation and -Deuteration of Alkenes Triggered by Electroreduction of Difluoromethyltriphenylphosphonium Bromide

It is significant to develop novel difluoromethylation methods because of the important roles of difluoromethyl groups in the medicinal chemistry and material industries. Here, we developed a novel difluoromethylation-carboxylation and difluoromethylation-deuteration method triggered by a difluoromethyl radical generated by electroreduction of stable and easily available difluoromethyltriphenylphosphonium bromide. Various molecules containing difluoromethyl and carboxyl or deuterium groups can be synthesized through this method. The establishment of this method will provide an alternative to radical difluoromethylation reactions.

Photocatalytic hydrofluoroalkylation of alkenes with carboxylic acids

Incorporation of fluoroalkyl motifs in pharmaceuticals can enhance the therapeutic profiles of the parent molecules. The hydrofluoroalkylation of alkenes has emerged as a promising route to diverse fluoroalkylated compounds; however, current methods require superstoichiometric oxidants, expensive/oxidative fluoroalkylating reagents and precious metals, and often exhibit limited scope, making a universal protocol that addresses these limitations highly desirable. Here we report the hydrofluoroalkylation of alkenes with cheap, abundant and available fluoroalkyl carboxylic acids as the sole reagents. Hydrotrifluoro-, difluoro-, monofluoro- and perfluoroalkylation are all demonstrated, with broad scope, mild conditions (redox neutral) and potential for late-stage modification of bioactive molecules. Critical to success is overcoming the exceedingly high redox potential of feedstock fluoroalkyl carboxylic acids such as trifluoroacetic acid by leveraging cooperative earth-abundant, inexpensive iron and redox-active thiol catalysis, enabling these reagents to be directly used as hydroperfluoroalkylation donors without pre-activation. Preliminary mechanistic studies support the radical nature of this cooperative process.

Manganese/Cobalt Bimetallic Relay Catalysis for Divergent Dehydrogenative Difluoroalkylation of Alkenes

The involvement of manganese radical for halogen atom transfer (XAT) reactions has been esteemed as one reliable method but encountered with limited catalytic models. In this paper, a novel bimetallic relay catalysis of Mn2 (CO)10 and cobaloxime has been developed for divergent dehydrogenative difluoroalkylation of alkenes using commercially available difluoroalkyl bromides. A wide range of structurally diverse terminal, cyclic and internal alkenes as well as tetrasubstituted alkenes are found to be good coupling partners to deliver difluoroalkylated allylic products and difluoromethylated cyclic products, accompanied with the production of H2 as the by-product. This bimetallic relay strategy features broad substrate scope, mild reaction conditions and excellent functional group compatibility. Its success represents an important step-forward to expedite the construction of a rich library of difluoroalkylated products.

[(SIPr)Ag(CF2 H)]: A Shelf-Stable, Versatile Difluoromethylation Reagent

Due to its unique physical and electrophilic properties, the difluoromethyl group (-CF2 H) has been playing an irreplaceable role in the field of pharmaceutical and agrochemical industry. Methods that could efficiently incorporate the difluoromethyl group into the target molecules are increasing in the recent years. Developing a stable and efficient difluoromethylating reagent is thus highly attractive. In this review, we describe the development of a nucleophilic difluoromethylation reagent [(SIPr)Ag(CF2 H)], including its elemental reaction, difluoromethylation reaction with different types of electrophiles, and its application in the synthesis of a nucleophilic and an electrophilic difluoromethylthiolating reagent.

Photocatalytic Hydro Tri/Difluoromethylation of Alkenes with Bench Stable Tri/Difluoromethylating Reagents

Herein, we demonstrate the synthesis and characterization of bench stable tri/difluoromethylating reagents and their potential applications in redox neutral hydro tri/difluoromethylation of alkenes enabled by visible light. The new tri/difluoromethylating reagents are obtained on a gram-scale through simply cyclocondensation of commercially available anthranilamide with phenyltrifluoro or difluoromethyl ketone. Preliminary mechanistic studies indicated that a canonical photoredox catalytic cycle is being operative. DFT studies support this and further reveal that deprotonation occurs before radical cleavage. DFT studies also show that the better yield with HCF2 reagent is attributed to the favorable expulsion of the corresponding radical moiety.

Nickel-Catalyzed Markovnikov-Selective Hydrodifluoromethylation of Alkynes Using BrCF2 H

A Markovnikov-selective hydrodifluoromethylation of alkynes with BrCF2 H via nickel catalysis is described. This protocol proceeds via a migratory insertion of nickel hydride to alkyne followed by a CF2 H-coupling, enabling straightforward access to diverse branched CF2 H-alkenes with high efficiency and exclusive regioselectivity. The mild condition applies to a wide array of aliphatic and aryl alkynes with good functional group compatibility. Mechanistic studies are presented to support the proposed pathway.

Visible-light-induced reactions of methylenecyclopropanes (MCPs)

Diverse, visible-light-induced transformations of methylenecyclopropanes (MCPs) have been reported in recent years, attracting significant attention from synthetic chemists. As readily accessible strained molecules, MCPs have sufficient reactivity to selectively generate different target products, through reactions with various radical species upon visible-light irradiation under regulated reaction conditions. These transformations can be classified into three subcategories of reaction pathway, forming ring-opened products, cyclopropane derivatives, and alkynes. These products include pharmaceutical intermediates and polycyclic/heterocyclic compounds that are challenging to obtain using traditional methods. This review summarizes the recent advancements in this field.

Copper-Catalyzed Visible-Light-Induced Allylic Difluoromethylation of Unactivated Alkenes Using Difluoroacetic Acid

We herein describe a straightforward allylic difluoromethylation reaction of unactivated alkenes. Compared to cross-couplings of prefunctionalized allylic substrates for the construction of allylic CF₂H bonds, this reaction employs readily available alkenes as substrates under mild conditions. Difluoroacetic acid is used as an inexpensive and easy-to-handle source of CF₂H radical under visible light irradiation with PIDA. The copper catalyst plays an important role of diverting the reaction pathway toward allylic difluoromethylation as opposed to previously found hydrodifluoromethylation.

Organoboron Reagent-Controlled Selective (Deutero)Hydrodefluorination

(Deuterium-labeled) CF₂ H- and CFH₂ -moieties are of high interest in drug discovery. The high demand for the incorporation of these fluoroalkyl moieties into molecular structures has witnessed significant synthetic progress, particularly in the (deutero)hydrodefluorination of CF₃ -containing compounds. However, the controllable replacement of fluorine atoms while maintaining high chemoselectivity remains challenging. Herein, we describe the development of a selective (deutero)hydrodefluorination reaction via electrolysis. The reaction exhibits a remarkable chemoselectivity control, which is enabled by the addition of different organoboron sources. The procedure is operationally simple and scalable, and provides access in one step to high-value building blocks for application in medicinal chemistry. Furthermore, density functional theory (DFT) calculations have been carried out to investigate the reaction mechanism and to rationalize the chemoselectivity observed.

Copper-Catalyzed Hydroamination of gem-Difluoroalkenes Access to Diversified α-Difluoromethyl Amines

The difluoromethyl group (CF₂H) is of great importance in medicinal chemistry. We report herein an efficient method for the synthesis of diversified α-difluoromethyl amines through copper-catalyzed hydroamination of gem-difluoroalkenes, where the C-N bond formed via a α-CF₂H transition-metal intermediate. This new reaction proceeds through Cu-H insertion to gem-difluoroalkenes and gives valuable alkyl-CF₂H-containing compounds, which overcome the much more challenged β-F elimination from α-fluoroalkyl organocopper species. The reaction exhibits broad substrate scope with readily available starting materials and commercial catalysis.

Photocatalytic Late-Stage C-H Functionalization

The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C-H functionalization approaches that make use of low energy photons as a controllable energy source. Compared to traditional late-stage functionalization strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- and chemoselectivities. Merging the compelling benefits of photocatalysis with the late-stage functionalization workflow offers a potentially unmatched arsenal to tackle drug development campaigns and beyond. This Review highlights the photocatalytic late-stage C-H functionalization strategies of small-molecule drugs, agrochemicals, and natural products, classified according to the targeted C-H bond and the newly formed one. Emphasis is devoted to identifying, describing, and comparing the main mechanistic scenarios. The Review draws a critical comparison between established ionic chemistry and photocatalyzed radical-based manifolds. The Review aims to establish the current state-of-the-art and illustrate the key unsolved challenges to be addressed in the future. The authors aim to introduce the general readership to the main approaches toward photocatalytic late-stage C-H functionalization, and specialist practitioners to the critical evaluation of the current methodologies, potential for improvement, and future uncharted directions.

Visible-Light-Induced Nickel-Catalyzed Radical Cross-Couplings to Access α-Aryl-α-trifluoromethyl Alcohols

A photochemically induced nickel-catalyzed radical cross-coupling of phthalimido trifluoroethanol with aryl bromides to furnish α-aryl-α-trifluoromethyl alcohols is reported. This reaction proceeds via a photoinduced charge transfer of an electron donor-acceptor complex between Hantzsch ester and phthalimido trifluoroethanol, followed by 1,2-hydrogen atom transfer, to generate the α-hydroxytrifluoroethyl radical for the cross-coupling of aryl bromides. No exogenous photocatalysts or stoichiometric metal reductants are required in this mild and operationally simple protocol. Broad substrate compatibility and excellent functional group tolerance are observed.

Difluoromethylsulfonyl Imidazolium Salt for Difluoromethylation of Alkenes

Herein, we describe the design and synthesis of a difluoromethylsulfonyl imidazolium salt, which can act as a radical difluoromethylation reagent to achieve the challenging amino- and oxy-difluoromethylation of alkenes. Notably, the three steps for the synthesis of the imidazolium salt do not require any tedious distillation or column chromatography purification process, and the amino- and oxy-difluoromethylation paths are simply determined by the selection of reaction solvents.

Radical hydrodifluoromethylation of unsaturated C-C bonds via an electroreductively triggered two-pronged approach

Due to its superior ability in controlling pharmaceutical activity, the installation of difluoromethyl (CF₂H) functionality into organic molecules has been an area of intensive research. In this context, difluoromethylation of C-C π bonds mediated by a CF₂H radical have been pursued as a central strategy to grant access to difluoromethylated hydrocarbons. However, early precedents necessitate the generation of oxidative chemical species that can limit the generality and utility of the reaction. We report here the successful implementation of radical hydrodifluoromethylation of unsaturated C-C bonds via an electroreductively triggered two-pronged approach. Preliminary mechanistic investigations suggest that the key distinction of the present strategy originates from the reconciliation of multiple redox processes under highly reducing electrochemical conditions. The reaction conditions can be chosen based on the electronic properties of the alkenes of interest, highlighting the hydrodifluoromethylation of both unactivated and activated alkenes. Notably, the reaction delivers geminal (bis)difluoromethylated products from alkynes in a single step by consecutive hydrodifluoromethylation, granting access to an underutilized 1,1,3,3-tetrafluoropropan-2-yl functional group. The late-stage hydrodifluoromethylation of densely functionalized pharmaceutical agents is also presented.

Difluoromethylation of Unactivated Alkenes Using Freon-22 through Tertiary Amine-Borane-Triggered Halogen Atom Transfer

The application of abundant and inexpensive fluorine feedstock sources to synthesize fluorinated compounds is an appealing yet underexplored strategy. Here, we report a photocatalytic radical hydrodifluoromethylation of unactivated alkenes with an inexpensive industrial chemical, chlorodifluoromethane (ClCF₂H, Freon-22). This protocol is realized by merging tertiary amine-ligated boryl radical-induced halogen atom transfer (XAT) with organophotoredox catalysis under blue light irradiation. A broad scope of readily accessible alkenes featuring a variety of functional groups and drug and natural product moieties could be selectively difluoromethylated with good efficiency in a metal-free manner. Combined experimental and computational studies suggest that the key XAT process of ClCF₂H is both thermodynamically and kinetically favored over the hydrogen atom transfer pathway owing to the formation of a strong boron-chlorine (B-Cl) bond and the low-lying antibonding orbital of the carbon-chlorine (C-Cl) bond.

Organocatalytic Three-Component Acyldifluoromethylation of Vinylarenes via N-Heterocyclic Carbene-Catalyzed Radical Relay

We herein describe an N-hetercyclic carbene-catalyzed three-component acyldifluoromethylation of vinylarenes, aldehydes, and NaSO₂CF₂H. This organocatalytic approach provides a practical route for the synthesis of pharmaceutically relevant α-aryl-β-difluormethyl ketones without the need for transition metals or photocatalysts. The late-stage acyldifluoromethylation of drug analogues was also demonstrated. The reaction design employs NaSO₂CF₂H as the source of the CF₂H radical in the presence of an oxidant for the radical relay.

Straightforward Synthesis of Alkyl Fluorides via Visible-Light-Induced Hydromono- and Difluoroalkylations of Alkenes with α-Fluoro Carboxylic Acids

We herein report the first visible-light-induced hydromono- and difluoroalkylations of alkenes with inexpensive and easily accessible α-fluoro carboxylic acids. This metal-free protocol exhibits mild conditions, high efficiency, and excellent functional-group tolerance, providing a straightforward approach to mono- and difluoroalkylated alkanes. Moreover, the fluorine effect on the hydrofluoroalkylation reaction is discussed in detail.

Acyldifluoromethylation Enabled by NHC-Photoredox Cocatalysis

With the continued interest in the properties of the difluoromethyl (CF₂H) group, small molecules with alkyl-CF₂H motifs have gained increasing attention. However, concise and efficient synthetic protocols to achieve these structures are still urgently needed. Herein, we report a new acyldifluoromethylation of inert alkenes via a synergistic NHC-photoredox catalysis featuring broad substrate scope and good functional group tolerance.

Difluoromethylarylation of Alkynes from [Bis(difluoroacetoxy)iodo]benzene: Access to CF2H-Containing Dibenzazepines

A photoinduced radical difluoromethylarylation via tandem addition-cyclization of alkynes with easily available [bis(difluoroacetoxy)iodo]benzene is accomplished, providing a straightforward and practical route for the construction of difluoromethylated dibenzazepines. Various sensitive functional groups can be compatible under photoinduced conditions. Mechanism investigation reveals that this transformation is initiated by the addition of alkyne with difluoromethyl radical, generated in situ from [bis(difluoroacetoxy)iodo]benzene.

Difunctionalization of gem-Difluoroalkenes via Photoredox Catalysis: Synthesis of Diverse α,α-Difluoromethyl-β-alkoxysulfones

Visible-light-promoted alkoxysulfonylation of gem-difluoroalkenes using sulfonyl chlorides and alcohols has been developed. The reaction exhibits a relatively broad substrate scope with excellent functional group compatibility. This synthesis method includes an atom transfer radical addition-like process. The products can be used as platform molecules for further modification.

Direct C(sp3)−H Difluoromethylation via Radical-Radical Cross-Coupling by Visible-Light Photoredox Catalysis

Herein, the radical-radical cross-coupling strategy for direct difluoromethylation of C(sp3)−H bond is reported. This transformation was readily accomplished under transition metal-free photoredox catalysis in the presence of 3 mol% of...

State of knowledge in photoredox-catalysed direct difluoromethylation

The combination of visible light photoredox catalysis with direct difluoromethylation has allowed the synthesis of a large choice of CF2H-containing value-added molecules under very mild reaction conditions.

Difluoromethylarylation of α, β- Unsaturated Amides via a Photocatalytic Radical Smiles Rearrangement

A photocatalytic Smiles rearrangement, triggered by radical difluoromethylation of conjugated arylsulfonylated amides, was developed to construct both β-difluoromethyl amide and heterocyclic scaffolds selectively. This transformation features mild conditions and broad...

Highly Regio- and Enantioselective Hydrosilylation of gem-Difluoroalkenes via Nickel Catalysis

The synthesis of small organic molecules with a difluoromethylated stereocenter is particularly attractive in drug discovery. Herein, we developed an efficient method for the direct generation of difluoromethylated stereocenters through Ni(0)-catalyzed regio - and enantioselective hydrosilylation of gem -difluoroalkenes. The reaction also represents the enantioselective construction of carbon(sp 3 )-silicon bonds with nickel catalysis, which provides an atom- and step-economical synthesis route of high-value optically active α-difluoromethylsilanes. This protocol features with readily available starting materials and commercial chiral catalysis, broad substrates spanning a range of functional groups with high yield (up to 99% yield) and excellent enantioselectivity (up to 96% ee). The enantioenriched products undergo a variety of stereospecific transformations. Preliminary mechanistic studies were performed.

Difluoromethyl Radical Triggered Tandem Reaction of N-Allyl Amides to Difluoromethylated β-Amino Alcohols by Photoredox Catalysis

An elegant tandem reaction process for transferring N-allyl amide into CF₂H-β-amino alcohol is described. This approach proceeded smoothly under visible light irradiation in the presence of a 3 mol % Ir complex, exhibiting a broad substrate scope and functional group tolerance, and a variety of CF₂H-β-amino alcohols were readily accessed in good to excellent yields under mild conditions. The reliable mechanistic studies revealed that sequential difluoromethyl radical addition/carbocation trap/rearrangement is involved.