Metal-Free Activation of C–I Bonds and Perfluoroalkylation of Alkenes with Visible Light Using Phosphine Catalysts

Catalytic 1,2-Radical Acyloxy Migration: A Strategy to Access Novel Chemical Space and Reaction Profiles

ConspectusRadical migration represents a powerful strategy for reaction discovery and development in organic synthesis, offering access to unprecedented functional molecules and chemical space. In this Account, we describe our contributions to the field, particularly focusing on 1,2-radical acyloxy migration (RAM), a process involving the transposition of a radical and an acyloxy group. We highlight its application in carbohydrate modification and allyl carboxylate trifunctionalization, demonstrating how this reactivity enables the streamlined synthesis of novel glycomimetics and facilitates selective 1,2,3-trifunctionalization of allyl carboxylates. These advances establish 1,2-RAM as a versatile platform for catalytic radical transformations, unlocking new opportunities in reaction development and functional molecule design.Our approach leverages excited-state palladium and ground-state nickel catalysis to modify carbohydrates, specifically at the C2 position. This strategy enables C2-deoxy-hydrogenation, deuteration, iodination, alkenylation, allylation, ketonylation, and arylation reactions, providing direct access to unprecedented glycomimetics. These transformations streamline the synthesis of structurally diverse glycomimetics, facilitating the discovery and development of carbohydrate-based functional molecules. Furthermore, the mild reaction conditions and high functional group tolerance of these catalytic systems make them particularly attractive for late-stage functionalization, broadening their applicability in complex molecule synthesis.Beyond carbohydrates, we have extended 1,2-RAM reactivity to achieve unprecedented 1,2,3-trifunctionalization of allyl carboxylates. By employing excited-state phosphine catalysis, we demonstrate a 1,3-carbobromination reaction accompanied by an acyloxy shift. This proof-of-concept study lays the foundation for developing a broader range of 1,2,3-trifunctionalization reactions, effectively transforming allyl carboxylates into substituted isopropyl carboxylate donors. This advancement expands the synthetic utility of allyl carboxylates, enabling the rapid construction of structurally diverse molecular scaffolds.In summary, the 1,2-RAM reactivity opens a new avenue for reaction discovery and development, granting access to new functional molecules and chemical space. The mild conditions, broad functional group compatibility, and unique reactivity of this approach make it a valuable tool for chemical synthesis. We anticipate that merging 1,2-RAM with other catalytic platforms will further advance bond disconnection strategies, provide access to new functional molecules, and expand the frontiers of chemical synthesis.

Stereoselective Synthesis of 1,2-cis-α-Glycosyl Thiols and Trehalose-Type α,α'-Thiodisaccharides by Cryo Thiol-Ene Photocoupling - Thio-Click Reaction in Frozen State

α-Glycosyl thiols are key building blocks for the formation of stable thioglycoside mimetics of widespread and biologically relevant α-O-glycosides, which urges their efficient synthesis. Here, we demonstrate that the photoinitiated radical-mediated addition of thioacetic acid to 2-substituted glycals followed by selective S-deacetylation is a generally applicable and fully stereoselective method for the synthesis of 1,2-cis-α-glycosyl thiols. The low reactivity of thioacetic acid in the radical reaction was overcome by carrying out the reaction in AcOH at -80 °C, in frozen state, with UVA irradiation, achieving high yields irrespective of the sugar configurations. For effective irradiation and simultaneous effective cooling, a self-made spiral vessel reactor was used, which also enables large-scale synthesis. By subjecting 1,2-cis-α-1-thiosugars to a second thiol-ene coupling reaction with 2-substituted glycals, 34 trehalose-type symmetrical and unsymmetrical α,α'-thiodi- and oligosaccharides were obtained with full stereoselectivity. Moreover, the oxidation of α-1-thiosugars provided an easy access to α,α'-diglycosyl disulfides.

Electron-Donor-Mediated Divergent Transformation of Br-RF via EDA Complex for the Synthesis of Fluorine-Containing Oxindoles and Amides

We have developed an unprecedented electron-donor-controlled divergent reaction between N-alkylsulfonylated acrylamides and Br-RF, facilitated by an electron donor-acceptor (EDA) complex, for the synthesis of fluorine-containing oxindoles and amides. Key to this divergent transformation is the EDA complex generation by altering electron donors. This approach has several advantages, such as broad substrate scope, being metal-catalyst- and photocatalyst-free, and having good functional group tolerance.

Synthesis of Perfluoroalkylated Pyrazoles from α-Perfluoroalkenylated Aldehydes

Within this study, we report a simple two-step process for the synthesis of perfluoroalkylated pyrazoles from aliphatic aldehydes. In the photocatalytic first step, the aldehydes are transformed into the corresponding perfluoroalkylated enals, which then undergo nucleophilic attack by hydrazine and subsequent ring closure, providing the fluorinated 3,4-substituted pyrazole products in a 64-84% yield. Using triphenylphosphine and imidazolidinone as organocatalysts, the method is operationally simple and omits heavy metal-containing waste.

Visible Light-Induced Oxy-perfluoroalkylation of Olefins via Ternary Electron Donor-Acceptor Complexes

Perfluoroalkyl iodides generally formed electron donor-acceptor (EDA) complexes by halogen bonding with a nitrogen atom containing Lewis bases. Since the electronegativity of the oxygen atom is stronger than that of the nitrogen atom, the resulting Rf-I···O-type halogen bonding EDA complex is less inclined to undergo electron transfer. Here, we reported rare ternary EDA complexes among perfluoroalkyl iodide, oxygen atom, and base. Mechanism experiments and density functional theory theoretical (DFT) calculations indicated that a base-promoted proton-coupled electron transfer (PCET) process was involved in this photochemical reaction. The intracomplex electron transfer event generated two radical species, perfluoroalkyl radical and TEMPO radical, enabling the subsequent oxy-perfluoroalkylation of olefins.

Regio- and stereoselective access to highly substituted vinylphosphine oxides via metal-free electrophilic phosphonoiodination of alkynes

In general, the P-centered ring-opening of quaternary phosphirenium salts (QPrS) predominantly leads to hydrophosphorylated products, while the C-centered ring-opening is primarily confined to intramolecular nucleophilic reactions, resulting in the formation of phosphorus-containing cyclization products instead of difunctionalized products generated through intermolecular nucleophilic processes. Here, through the promotion of ring-opening of three-member rings by iodine anions and the quenching of electronegative carbon atoms by iodine cations, we successfully synthesize β-functionalized vinylphosphine oxides by the P-addition of QPrS intermediates generated in situ. Multiple β-iodo-substituted vinylphosphine oxides can be obtained with exceptional regio- and stereo-selectivity by reacting secondary phosphine oxides with unactivated alkynes. In addition, a variety of β-functionalized vinylphosphine oxides converted from C-I bonds, especially the rapid construction of benzo[b]phospholes oxides, demonstrates the significance of this strategy.

Perfluoroalkylation of Triarylamines by EDA Complexes and Ulterior Sensitized [6π]-Electrocyclization to Perfluoroalkylated Endo-Carbazoles. Mechanistic and Photophysical Studies

Blue LEDs-irradiation of a mixture of N,N,N',N'-tetramethylethylenediamine (TMEDA) and perfluoroalkyl iodides (RF-I) - Electron Donor Acceptor (EDA)-complex - in the presence of triphenylamines (TPAs) in an aqueous solvent mixture afforded mono-perfluoroalkylated triphenylamines (RF-TPA) in good yields. These RF-TPA were further subjected to acetone-sensitized [6π]-electrocyclization at 315 nm-irradiation affording exclusively perfluoroalkylated endo-carbazole derivatives (RF-CBz) in quantitative yields. Mechanistic studies and photophysical properties of products are studied.

Photochemical Synthesis of Lactones, Cyclopropanes and ATRA Products: Revealing the Role of Sodium Ascorbate

Light-mediated processes have received significant attention, since they have re-surfaced unconventional reactivity platforms, complementary to conventional polar chemistry. γ-Lactones and cyclopropanes are prevalent moieties, found in numerous natural products and pharmaceuticals. Among various methods for their synthesis, light-mediated protocols are coming to the spotlight, although these are contingent upon the use of photoorgano- or metal-based catalysts. Herein, we introduce a novel photochemical activation of iodo-reagents via the use of cheap sodium ascorbate or ascorbic acid to enable their homolytic scission and addition onto double bonds. The developed protocol was applied successfully to the formal [3+2] cycloaddition for the synthesis of γ-lactones, traditional atom transfer radical addition (ATRA) reactions and the one-pot two-step conversion of alkenes to cyclopropanes. In all cases, the desired products were obtained in good to high yields, while the reaction mechanism was thoroughly investigated. Depending on the nature of the iodo-reagent, a halogen or a hydrogen-bonded complex is formed, which initiates the process.

Phototriggered Fluoroalkylation/Cyclization of Unactivated 1-Acryloyl-2-cyanoindoles: Synthesis of RCOCF2-Substituted Pyrrolo[1,2-a]indolediones

A photochemical approach toward RCOCF2-substituted pyrrolo[1,2-a]indolediones was developed by the radical cascade difluoroalkylation/cyclization reaction of unactivated 1-acryloyl-2-cyanoindoles with ethyl iododifluoroacetate or iododifluoramides under visible-light irradiation. This transition-metal- and photosensitizer-free protocol afforded diverse difluoroalkylated pyrrolo[1,2-a]indolediones in moderate to good yields under mild reaction conditions. Most appealingly, the reaction can proceed smoothly under sunlight irradiation, which opens a new avenue toward difluoroalkylated pyrrolo[1,2-a]indolediones.

Photoinduced selective perfluoroalkylation of terminal alkynes via electron donor-acceptor complexes

Herein, we report a photoinduced selective perfluoroalkylation of terminal alkynes driven by the noncovalent interaction between a thymol anion and fluoroalkyl iodides. By precisely tuning the reaction solvent, a wide range of 37 structurally diverse perfluoroalkylated alkynes and alkenes, including ibuprofen, empagliflozin, galactose, isoxepac and indomethacin, were obtained in up to 92% yields. Mechanistic studies reveal the formation of EDA complexes between the thymol anion and fluoroalkyl iodides. This strategy may provide an important complement to traditional approaches to prepare useful perfluoroalkylated alkynes and alkenes.

Visible Light-Assisted Ring-Opening of Cyclic Ethers with Carboxylic Acids Mediated by Triphenylphosphine and N-Halosuccinimides

The ring-opening of cyclic ethers (epoxide, oxetane, THF, and THP) by carboxylic acids was achieved by using N-iodosuccinimide (NIS) or N-bromosuccinimide (NBS) and triphenylphosphine under blue light. The corresponding ω-haloalkyl carboxylates were obtained under mild reaction conditions. The reaction is believed to work through a halogen bond complex between NIS (or NBS) and triphenylphosphine, which, upon irradiation with blue light, produces the key phosphine radical cation intermediate that initiates the ring-opening reactions.

Shining light on halogen-bonding complexes: a catalyst-free activation mode of carbon-halogen bonds for the generation of carbon-centered radicals

The discovery of new activation modes for the creation of carbon-centered radicals is a task of great interest in organic chemistry. Classical activation modes for the generation of highly reactive radical carbon-centered intermediates typically relied on thermal activation of radical initiators or irradiation with unsafe energetic UV light of adequate reaction precursors. In recent years, photoredox chemistry has emerged as a leading strategy towards the catalytic generation of C-centered radicals, which enabled their participation in novel synthetic organic transformations which is otherwise very challenging or even impossible to take place. As an alternative to these activation modes for the generation of C-centered radicals, the pursuit of greener, visible-light initiated reactions that do not necessitate a photoredox/metal catalyst has recently caught the attention of chemists. In this review, we covered recent transformations, which rely on photoactivation with low-energy light of a class of EDA complexes, known as halogen-bonding adducts, for the creation of C-centered radicals.

Photocatalytic Cascade Cyclization of Aryl Haloalkynyl Ketones Forming Cyclopenta[b]naphthalene Derivatives

An efficient metal-free, photoredox-mediated cascade cyclization of aryl 1-haloalk-5-ynyl ketones has been developed. Using catalytic amounts of eosin Y (EY) and EtNMe₂ as a reductive quencher, various aryl 1-haloalk-5-ynyl ketones have been transformed into the corresponding cyclization products in up to 98% yield. As a result, synthetic access to differently α-functionalized cyclopenta[b]naphthones and direct construction of cyclopenta[b]naphtholes has been developed.

Expanding Reaction Profile of Allyl Carboxylates via 1,2-Radical Migration (RaM): Visible-Light-Induced Phosphine-Catalyzed 1,3-Carbobromination of Allyl Carboxylates

Allyl carboxylates are useful synthetic intermediates in a variety of organic transformations, including catalytic nucleophilic/electrophilic allylic substitution reactions and 1,2-difunctionalization reactions. However, the catalytic 1,3-difunctionalization of allyl carboxylates remains elusive. Herein, we report the first photoinduced, phosphine-catalyzed 1,3-carbobromination of allyl carboxylates, affording a range of valuable substituted isopropyl carboxylates (sIPC). The transformation has broad functional group tolerance, is amenable to the late-stage modification of complex molecules and gram-scale synthesis, and expands the reaction profiles of allyl carboxylates and phosphine catalysis. Preliminary experimental and computational studies suggest a non-chain-radical mechanism involving the formation of an electron donor-acceptor complex, 1,2-radical migration (RaM), and Br-atom transfer processes. We anticipate that the 1,2-RaM reactivity of allyl carboxylates and the phosphine-catalyzed radical reaction will both serve as a platform for the development of new transformations in organic synthesis.

Three-Component Perfluoroalkylvinylation of Alkenes Enabled by Dual DBU/Fe Catalysis

Herein, a simple and efficient strategy that involves dual 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)/iron-catalyzed alkene perfluoroalkylvinylation by using perfluoroalkyl iodides and 2-aminonaphthalene-1,4-diones as coupling partners is demonstrated. In terms of the developed catalytic system, various styrenes and aliphatic alkenes are well-tolerated, leading to the accurate preparation of perfluoroalkyl-containing 2-aminonaphthalene-1,4-diones in excellent regioselectivity. Moreover, the protocol can be readily applied in late-stage modifications of natural products and pharmaceuticals. The title reactions are featured by easily accessible and inexpensive catalysts and substrates, broad substrate applicability, and mild reaction conditions. Mechanistic investigations reveal a tandem C-I cleavable alkylation and C-C vinylation enabled by cooperative DBU/iron catalysis.

Metal-free visible-light-induced hydroxy-perfluoroalkylation of conjugated olefins using enamine catalyst

We developed a simple and sustainable method for the hydroxy-perfluoroalkylation of electron-deficient conjugated olefins and styrenes. In this protcol, in situ generated enamine forms electron-donor-accepter (EDA) complexes with perfluoroalkyl iodide, and reaction proceed with visible-light irradiation. Tertiary amine also interacts with perfluoroalkyl iodide via halogen-bonding, promoting the perfluoroalkyl radical generation. This reaction does not require any transition-metal or photoredox catalyst, and gaseous oxygen is used as the green hydroxy source. Moreover, various commercially available substrates and perfluoroalkyl iodides were tolerated, affording the desired hydroxy-perfluoroalkylated products in good to moderate yields (>50 examples, up to 90%).

Visible-Light-Enabled Ph3P/LiI-Promoted Tandem Radical Trifluoromethylation/Cyclization/Iodination of 1,6-Enynes with Togni's Reagent

We report the visible-light-induced Ph₃P/LiI-promoted intermolecular cascade trifluoromethyl radical addition/5-exo-dig cyclization/iodination of 1,6-enynes with Togni's reagent using LiI as the iodine source without the need of the transition metal, oxidant, and base. This reaction promises to be a useful method for the preparation of trifluoromethyl-substituted and vinyl C-I bond-containing pyrrolidines and benzofuran products with good regioselectivity and functional-group tolerance under ambient conditions.

Iodoperfluoroalkylation of unactivated alkenes via pyridine-boryl radical initiated atom-transfer radical addition

The pyridine/bis(pinacolate)diboron combination has been found to be able to initiate the iodoperfluoroalkylation of unactivated alkenes with perfluoroalkyl iodides. Theoretical calculations and control experiments indicate that the atom transfer radical addition mechanism is responsible for the formation of iodoperfluoroalkylation products. This metal-free and photo-free strategy is applicable to a wide range of perfluoroalkyl iodides and unactivated alkenes with good functional group tolerance. Further applications in iodoperfluoroalkylation of organic semiconductor-relevant or bioactive molecules demonstrate the synthetic potential of this method.

Recent Advances in Photoinduced Perfluoroalkylation Using Perfluoroalkyl Halides as the Radical Precursors

Perfluoroalkylation is one of the most important methods for the introduction of multiple fluorine atoms into organic molecules in a single step. The use of photoinduced technology is a common strategy that uses the outstanding oxidation or reduction ability of a photo­redox catalyst in its excited state to generate perfluoroalkyl radicals from perfluoroalkyl halides. The perfluoroalkyl radicals thus obtained can undergo various subsequent reactions under mild conditions, such as ATRA reaction of alkenes, alkynes, and 1,n-enynes; carbo/heteroperfluoroalkylation of alkenes and isocyanides; and C–H/F perfluoroalkyl­ation. This allows the expedient incorporation of various perfluoroalkyl groups into the molecular motifs. Perfluorinated functional groups are still in demand in pharmaceutical and material sciences; this short review discusses recent advances in photoinduced perfluoroalkylation methodologies and technologies.

1 Introduction

2 Photocatalytic Perfluoroalkylation of Alkenes, Alkynes, and 1,n- Enynes

3 Photocatalytic Carboperfluoroalkylation or Heteroperfluoro­alkylation of Alkenes, Alkynes, Isocyanides, and Hydrazones

4 Photocatalytic ATRE Reactions of Alkenes with Perfluoroalkyl Halides­

5 Photocatalytic C–X (X = H, F) Bond Perfluoroalkylation

6 Continuous Flow Strategies in Photocatalytic Perfluoroalkylation

7 Conclusions

Electron donor–acceptor complex-catalyzed photoredox reactions mediated by DIPEA and inorganic carbonates

A DIPEA–NHPI ester–inorganic carbonate catalytic EDA complex is reported as an efficient and sustainable radical generation platform for developing photocatalytic reactions.

Halogen bond promoted aryl migration of allylic alcohols under visible light irradiation

A simple and catalyst-free radical addition/1,2-aryl migration cascade process of ally alcohol driven by halogen bond was developed under visible light irradiation, featuring mild conditions, practical procedures, and broad substrate scope.

Visible Light-induced Phosphine-Catalyzed Perfluoroalkylation of Indoles

A photo-induced, catalytic phosphine-promoted perfluoroalkylation reaction of indole molecules is developed. Inexpensive and readily available PPh3 is used in a catalytic amount as the sole reaction initiator in this protocol....

Water facilitated photolysis of perfluoroalkyl iodides via halogen bonding

A strategy for the efficient water facilitated photolysis of perfluoroalkyl iodide has been established for the synthesis of various perfluoroalkylated products.

Construction of sterically congested oxindole derivatives via visible-light-induced radical-coupling

The oxindole scaffold represents an important structural feature in many natural products and pharmaceutically relevant molecules. Herein, we report a visible-light-induced modular methodology for the synthesis of complex 3,3'-disubstituted oxindole derivatives. A library of valuable fluoroalkyl-containing highly sterically congested oxindole derivatives can be synthesized by a catalytic three-component radical coupling reaction under mild conditions (metal & photocatalyst free, >80 examples). This strategy shows high functional group tolerance and broad substrate compatibility (including a wide variety of terminal or non-terminal alkenes, conjugated dienes and enynes, and a broad array of polyfluoroalkyl iodide and oxindoles), which enables modular modification of complex drug-like compounds in one chemical step. The success of solar-driven transformation, large-scale synthesis, and the late-stage functionalization of bioactive molecules, as well as promising tumor-suppressing biological activities, highlights the potential for practical applications of this strategy. Mechanistic investigations, including a series of control experiments, UV-vis spectroscopy and DFT calculations, suggest that the reaction underwent a sequential two-step radical-coupling process and the photosensitive perfluoroalkyl benzyl iodides are key intermediates in the transformation.

Facile photochemical synthesis of main-chain-type semifluorinated alternating copolymers catalyzed by conventional amines or halide salts

In this work, we report a much simpler and low-cost method to prepare main-chain-type semifluorinated alternating copolymers by the formation of a halogen bond (XB) complex between α,ω-diiodoperfluoroalkanes and amines/halide salts. It is interesting that the terminal iodine functional group of the polymer chains is easily lost in the amine-promoted system, while the loss can be significantly reduced by adding a small amount of water. Importantly, the system promoted by halide salts can ensure complete retention of the iodine functional group. Overall, the establishment of this method provides a new strategy for designing smart fluoropolymer materials in a green and environmentally friendly facile manner under irradiation with visible light at room temperature.

Photoinduced Atom Transfer Radical Addition Reaction of Olefins with α-Bromo Carbonyls

The irradiation of halogen-bonded complexes with light leads to the homolysis of carbon-halogen bonds and the formation of the corresponding carbon radical species. However, the only methodology reported for these halogen-bonding complexes is using CBr₄ as the halogen-bond donor and its applicability is of great interest. In this study, the atom transfer radical addition (ATRA) reaction of olefins using bromomalonates as halogen-bonding donors was developed. Using 4-phenylpyridine as the halogen-bonding acceptor, the desired reaction proceeded well under external irradiation of 380 nm light to furnish the corresponding ATRA reaction product. The ATRA reaction was effective in generating the corresponding products for a variety of olefins. Furthermore, the ATRA reaction was applicable to bulky ketones, substrates, and malonate esters. The intermediates of the reaction were identified and a plausible reaction mechanism was proposed.

Gold-Catalyzed One-Pot Synthesis of Polyfluoroalkylated Oxazoles from N-Propargylamides Under Visible-Light Irradiation

A gold-catalyzed synthesis of polyfluoroalkylated oxazoles from N-propargylamides under visible-light irradiation has been developed. These reactions display excellent compatibility of radicals and gold catalysts under visible-light irradiation. Mechanistic experiments indicate that polyfluoroalkyl iodides play a dual role in enhanced compatibility of radicals and gold catalysts through assisted protodeauration of vinyl gold and reactivated the gold catalyst. In addition, PPh₃ AuNTf₂ not only activates N-propargylamide to generate vinyl gold intermediate, but also greatly promotes homolysis of polyfluoroalkyl iodides under blue light irradiation.

Synthesis and Photochemical Application of Hydrofluoroolefin (HFO) Based Fluoroalkyl Building Block

A novel fluoroalkyl iodide was synthesized on multigram scale from refrigerant gas HFO-1234yf as cheap industrial starting material in a simple, solvent-free, and easily scalable process. We demonstrated its applicability in a metal-free photocatalytic ATRA reaction to synthesize valuable fluoroalkylated vinyl iodides and proved the straightforward transformability of the products in cross-coupling chemistry to obtain conjugated systems.

Atom-transfer radical addition of fluoroalkyl bromides to alkenes via a photoredox/copper catalytic system

A method for the addition of fluorinated alkyl bromides to alkenes is described. The reaction proceeds under visible light irradiation in the presence of two catalysts: Ir(ppy)₃ and N-heterocyclic carbene ligated copper bromide (IMesCuBr). The role of the iridium photocatalyst is to generate the fluoralkyl radical, while the copper promotes formation of the carbon-bromine bond.

Straightforward Synthesis of Fluorinated Enals via Photocatalytic α-Perfluoroalkenylation of Aldehydes

(Per)fluorinated substances represent an important compound class with regard to drug design and material chemistry. We found a mild, operationally simple, and inexpensive photocatalytic perfluoroalkenylation reaction giving tetrasubstituted, highly electron-deficient enals straight from aldehydes. This one-step reaction tolerates various functional groups and can be applied to a wide range of substrates giving the products in yields of 52-84%.

Phosphorus-Based Catalysis

Phosphorus-based organocatalysis encompasses several subfields that have undergone rapid growth in recent years. This Outlook gives an overview of its various aspects. In particular, we highlight key advances in three topics: nucleophilic phosphine catalysis, organophosphorus catalysis to bypass phosphine oxide waste, and organophosphorus compound-mediated single electron transfer processes. We briefly summarize five additional topics: chiral phosphoric acid catalysis, phosphine oxide Lewis base catalysis, iminophosphorane super base catalysis, phosphonium salt phase transfer catalysis, and frustrated Lewis pair catalysis. Although it is not catalytic in nature, we also discuss novel discoveries that are emerging in phosphorus(V) ligand coupling. We conclude with some ideas about the future of organophosphorus catalysis.

Copper-Catalyzed Perfluoroalkylation of Alkynyl Bromides and Terminal Alkynes

A copper-catalyzed one-pot perfluoroalkylation of alkynyl bromides and terminal alkynes has been disclosed, and the corresponding perfluoroalkylated alkynes could be attained in good to excellent yields. The new straightforward transformation shows high efficiency (0.01-0.5 mol % catalyst loading), broad substrate scope, and remarkable functional group tolerance and provides a facile approach for useful application in life and material sciences.

Synthetic reactions driven by electron-donor-acceptor (EDA) complexes

The reversible, weak ground-state aggregate formed by dipole-dipole interactions between an electron donor and an electron acceptor is referred to as an electron-donor-acceptor (EDA) complex. Generally, upon light irradiation, the EDA complex turns into the excited state, causing an electron transfer to give radicals and to initiate subsequent reactions. Besides light as an external energy source, reactions involving the participation of EDA complexes are mild, obviating transition metal catalysts or photosensitizers in the majority of cases and are in line with the theme of green chemistry. This review discusses the synthetic reactions concerned with EDA complexes as well as the mechanisms that have been shown over the past five years.

Visible light-driven fluoroalkylthiocyanation of alkenes via electron donor–acceptor complexes

The visible light-induced fluoroalkylthiocyanation of alkenes via electron donor–acceptor complexes of perfluoroalkyl iodide reagents and K₃PO₄ was disclosed.

Catalyst-free, visible-light-induced direct radical cross-coupling perfluoroalkylation of the imidazo[1,2-a]pyridines with perfluoroalkyl iodides

A mild and eco-friendly visible-light-induced direct radical cross-coupling perfluoroalkylation of the imidazo[1,2-a]pyridines with perfluoroalkyl iodides was established.

Photoinitiated stereoselective direct C(sp2)–H perfluoroalkylation and difluoroacetylation of enamides

Photoinitiated regio- and stereoselective C(sp²)–H perfluoroalkylation and difluoroacetylation of enamides are developed, furnishing biologically and physiologically privileged fluoro-containing enamide scaffolds.

Application of Bifunctional 2-Amino-1,4-naphthoquinones in Visible-Light-Promoted Photocatalyst-Free Alkene Perfluoroalkyl-Alkenylation

A simple and practical photochemical strategy for intermolecular perfluoroalkyl-alkenylation of alkenes with 2-amino-1,4-naphthoquinones and perfluoroalkyl iodides has been demonstrated under visible-light irradiation. Mechanistic studies reveal that easily available 2-amino-1,4-naphthoquinone substrates can serve as efficient photosensitizers to activate perfluoroalkyl iodides through a photoredox process. Therefore, the developed radical relay reaction proceeds smoothly without additional transition metals and photocatalysts.

Selective nickel-catalyzed fluoroalkylations of olefins

Mild and selective nickel-catalyzed trifluoromethylation and perfluoroalkylation reactions of alkenes were developed to provide fluorinated olefins, including natural products, pharmaceuticals, and variety of synthetic building blocks in good to excellent yields (38 examples). Control experiments, kinetic measurements and in situ EPR studies reveal the importance of radical species and the formation of 1,2-adducts as intermediates.

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.