Wonderful fusion of organofluorine chemistry and decarboxylation strategy

Nitrogen-Based Organofluorine Functional Molecules: Synthesis and Applications

Fluorine and nitrogen form a successful partnership in organic synthesis, medicinal chemistry, and material sciences. Although fluorine-nitrogen chemistry has a long and rich history, this field has received increasing interest and made remarkable progress over the past two decades, driven by recent advancements in transition metal and organocatalysis and photochemistry. This review, emphasizing contributions from 2015 to 2023, aims to update the state of the art of the synthesis and applications of nitrogen-based organofluorine functional molecules in organic synthesis and medicinal chemistry. In dedicated sections, we first focus on fluorine-containing reagents organized according to the type of fluorine-containing groups attached to nitrogen, including N-F, N-RF, N-SRF, and N-ORF. This review also covers nitrogen-linked fluorine-containing building blocks, catalysts, pharmaceuticals, and agrochemicals, underlining these components' broad applicability and growing importance in modern chemistry.

Configuration Retention in P-Trifluoromethyl Phosphine Enabled Rh(I)-Catalyzed Decarbonylative Coupling of Carboxylates and Boroxines

As compared with asymmetric catalysis, the memory of chirality provides another promising strategy to introduce chiral centers in light of numerous chiral starting materials that can be accessed. Decarboxylative coupling has become an important strategy for C-C or C-X bond formation over decades of development for its versatility and the low cost and structural diversity of carboxylic acids. However, the memory of chirality or more general configuration retention in this transformation has seldom been studied. Here, we report a novel π acceptor-type ligand P-trifluoromethyl phosphine enabled Rh(I)-catalyzed decarbonylative coupling of carboxylates and boroxines. The configuration of the α-carbon can be fully retained in this transformation for chiral, cis-, or trans-substrates. Several P-trifluoromethyl phosphine-Rh(I) carbonyl complexes were prepared and their v(CO) values were compared with known complexes, which indicated that the π-accepting property of the ligand is important to the decarbonylative reaction.

Selective Decarboxylative Fluorination of β-Keto Acids in Aqueous Media: 19F-NMR-Assisted Batch Optimization and Transfer to Continuous Flow

The selective decarboxylative fluorination of 3-oxo-3-phenylpropionic acid is used as a benchmark reaction to optimize it under biocompatible conditions in batch and to transfer it to continuous flow mode. The reaction conditions are varied with respect to temperature, fluorinating reagents, inorganic base additives, and pH, as these parameters have been identified as having a significant impact on the process. The formation of the products and any by-products is analyzed using gas chromatography (GC) and 19F nuclear magnetic resonance spectroscopy (NMR). Once optimal conditions have been determined, the reaction is carried out using an automated continuous laboratory synthesis system that features a mesostructured capillary reactor and an integrated 19F-NMR spectrometer for real-time monitoring of the reaction. The work presented here represents the initial phase of a multi-step continuous flow process that will include additional biocatalyzed downstream reactions in future applications.

FluoBase: a fluorinated agents database

Organofluorine compounds, owing to their unique physicochemical properties, play an increasingly crucial role in fields such as medicine, pesticides, and advanced materials. Fluorinated reagents are indispensable for developing efficient synthetic methods for organofluorine compounds and serve as the cornerstone of organofluorine chemistry. Equally important are fluorinated functional molecules, which contribute specific properties necessary for applications in pharmaceuticals, agrochemicals, and materials science. However, information about these agents' structure, properties, and functions is scattered throughout vast literature, making it inconvenient for synthetic chemists to access and utilize them effectively. Recognizing the need for a dedicated and organized resource, we present FluoBase-a comprehensive fluorinated agents database designed to streamline access to key information about fluorinated agents. FluoBase aims to become the premier resource for information related to fluorine chemistry, serving the scientific community and anyone interested in the applications of fluorine chemistry and machine learning for property predictions. FluoBase is freely available at https://fluobase.siochemdb.com . Scientific contribution FluoBase is a database designed to provide comprehensive information on the structures, properties, and functions of fluorinated agents and functional molecules. FluoBase aims to become the premier resource for fluorine chemistry, serving the scientific community and anyone interested in the applications of fluorine chemistry and machine learning for property predictions.

Radical-Initiated Dearomative Annulation of Tryptamine-Derived Isocyanides: Selective Synthesis of CF3-Substituted β-Aza-spiroindolines and β-Carbolines

A mild approach for synthesizing CF3-substituted β-aza-spiroindolines and β-carbolines from tryptamine-derived isocyanides via site-selective radical annulations has been reported. The crucial role of C2 substituents in the selective annulation process has been clarified. The approach shows good generality and practical applicability, highlighting its effectiveness and versatility.

Photoinduced fluoroalkylation-peroxidation of alkenes enabled by ligand-to-iron charge transfer mediated decarboxylation

We report here a photoinduced iron-catalyzed fluoroalkylation-peroxidation of activated and/or unactivated alkenes with fluoroalkyl carboxylic acids and hydroperoxide. The ligand-to-iron charge transfer strategy effectively overcomes the high redox potential of the fluoroalkyl carboxylic acids, facilitating the difunctionalization reaction to occur smoothly under mild reaction conditions. The late-stage functionalization of drug and natural product derivatives was also demonstrated.

A Metal-Free Direct Decarboxylative Fluoroacylation of Indole Carboxylic Acids with Fluorinated Acids

A straightforward preparation of diversified fluorinated indol-3-yl ketones was developed by the direct decarboxylative fluoroacylation of indole carboxylic acids. The reaction could be performed on a gram scale under net conditions. Neither a metal catalyst nor an additive was employed. This methodology featured simple reaction conditions, high efficiency, exclusive selectivity, a broad substrate scope, and easy operation, which allowed it to meet the green chemistry requirement of the modern pharmaceutical industry. Control experiments confirmed that a radical process might be involved in the tandem decarboxylative fluoroacylation sequence.

Iodine-mediated decarboxylative coupling to synthesize β-sulfonyl-ene-amines/2,3-diarythio-pyrroles from α-amino acids and sodium sulfinates

A novel process has been developed for the selective synthesis of β-sulfonyl-enamines and 2,3-diarylthiopyrroles. This process utilizes the decarboxylative coupling and β-C(sp3)-H functionalization of α-amino acids. In this reaction, iodine functions dually as a tandem catalyst to initiate the decarboxylation of α-amino acids and as an oxidant to facilitate the formation of organic sulfides. This innovative approach not only simplifies the synthesis but also enhances the yield and selectivity of the desired products.

Copper-Catalyzed Intramolecular Decarboxylative C(sp2)-Heteroatom Cross-Couplings: Mechanism Insights and Synthetic Applications

Decarboxylative C(sp2)-heteroatom cross-coupling reactions hold extraordinary potential for the sustainable preparation of biologically active scaffolds. Herein, we report a copper sulfate/1,10-phenathroline catalytic system for the decarboxylative intramolecular C(sp2)-O, C(sp2)-S, and C(sp2)-N coupling reactions leading to the construction of a series of benzo[b]furans, benzo[b]thiophenes, and indole derivatives from the corresponding coumarins, thiocoumarins, or quinolones, respectively. Our mechanistic study based on benzo[b]furan formation suggests a three-step process of the transformations, which consists of (i) base-mediated hydrolytic ring opening of coumarin, (ii) copper-oxygen co-initiated radical decarboxylation, and (iii) copper-catalyzed C-heteroatom cross coupling. Application of this method in the total synthesis of egonol, a bioactive natural product, was demonstrated successfully, with an overall yield of 51.7%.

Base-Promoted Nucleophilic Phosphorylation of Benzyl Fluorides via C(sp3)-F Cleavage

Herein, a transition-metal-free phosphorylation of benzyl fluorides with P(O)-H compounds is disclosed. In the presence of tBuOK, various benzyl fluorides react with P(O)-H compounds to produce the corresponding benzyl phosphine oxides, phosphinates, and phosphonates in good to high yields. This base-promoted phosphorylation reaction offers a facile and general strategy for the construction of a C(sp3)-P bond.

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.

Decarboxylative Nucleophilic Fluorination of Aliphatic Carboxylic Acids

Herein, we present a decarboxylative nucleophilic fluorination of carboxylic acids with a silver catalyst. This strategy enables the synthesis of a myriad of diverse and valuable fluorinated motifs under mild conditions, demonstrating good functional-group tolerance and utility in late-stage functionalization. In contrast to traditional electrophilic fluorination, this nucleophilic method utilizes a more readily available nucleophilic fluorinating reagent, providing substantial advantages in terms of cost efficiency, broad substrate scope, and functional-group compatibility.

General Approach to Amides through Decarboxylative Radical Cross-Coupling of Carboxylic Acids and Isocyanides

Herein, we report a silver-catalyzed protocol for decarboxylative cross-coupling between carboxylic acids and isocyanides, leading to linear amide products through a free-radical mechanism. The disclosed approach provides a general entry to a variety of decorated amides, accommodating a diverse array of radical precursors, including aryl, heteroaryl, alkynyl, alkenyl, and alkyl carboxylic acids. Notably, the protocol proved to be efficient for decarboxylative late-stage functionalization of several elaborate pharmaceuticals, demonstrating its potential applications.

Zinc 1,1,2,2-Tetrafluoroethanesulfinate: A Synthetically Useful Oxidative and Photoredox Source of the 1,1,2,2-Tetrafluoroethyl Radical

1,1,2,2-Tetrafluoroethyl-containing molecules are of potential importance in drug discovery, but the efficient synthesis of such compounds is still relatively unexplored due to the lack of readily available reagents for the incorporation of the HCF2CF2 group. Herein, we introduce a new reagent, zinc 1,1,2,2-tetrafluoroethanesulfinate, which can be useful for the oxidative tetrafluoroethylation of arylboronic acids and heteroarenes as well as for a novel photoredox, three component hydro-tetrafluoroethylation of two alkenes of complementary reactivity.

O-Trifluoromethylation of Carboxylic Acids via the Formation and Activation of Acyloxy(phenyl)trifluoromethyl-λ3-Iodanes

Here we report the challenging O-trifluoromethylation of carboxylic acids via the formation and activation of acyloxy(phenyl)trifluoromethyl-λ3-iodanes. The method provides an easy access to various potentially valuable and hitherto elusive trifluoromethyl carboxylic esters. A remarkably wide range of substrates with commonly encountered functional groups are compatible with this reaction, including aromatic and aliphatic carboxylic acids, as well as Food and Drug Administration (FDA) approved drugs and pharmaceutically relevant molecules. The reaction mechanism and the origins of the enhanced reactivity by zinc chloride (ZnCl2) were discussed from experimental evidence and density functional theory (DFT) calculation.

eFluorination of Activated Alcohols Using Collidinium Tetrafluoroborate

Tertiary C-F bonds are important structural designs; however, they suffer from challenging synthesis. Current methodologies use corrosive amine-HF salts or expensive and hazardous catalysts and reagents. Our group recently introduced collidinium tetrafluoroborate as an efficient fluorinating agent for anodic decarboxyfluorination reactions. Nevertheless, tertiary carboxylic acids are less readily available and more challenging to prepare than their alcohol analogues. Herein we report a practical, mild, and cheap electrochemical method to achieve deoxyfluorination of hindered carbon centers.

Catalytic Asymmetric Difluoroalkylation Using In Situ Generated Difluoroenol Species as the Privileged Synthon

A robust and practical difluoroalkylation synthon, α,α-difluoroenol species, which generated in situ from trifluoromethyl diazo compounds and water in the presence of dirhodium complex, is disclosed. As compared to the presynthesized difluoroenoxysilane and in situ formed difluoroenolate under basic conditions, this difluoroenol intermediate displayed versatile reactivity, resulting in dramatically improved enantioselectivity under mild conditions. As demonstrated in catalytic asymmetric aldol reaction and Mannich reactions with ketones or imines in the presence of chiral organocatalysts, quinine-derived urea, and chiral phosphoric acid (CPA), respectively, this relay catalysis strategy provides an effective platform for applying asymmetric fluorination chemistry. Moreover, this method features a novel 1,2-difunctionalization process via installation of a carbonyl motif and an alkyl group on two vicinal carbons, which is a complementary protocol to the metal carbene gem-difunctionalization reaction.

Silver-Catalyzed Decarboxylative Remote Fluorination via a Zwitterion-Promoted 1,4-Heteroaryl Migration

A silver-catalyzed decarboxylative remote fluorination via a zwitterion-promoted 1,4-heteroaryl migration has been developed. A variety of heteroaryl-tethered benzyl fluorides have been readily synthesized with good regioselectivity under mild conditions. The zwitterion of the substrate is suggested to accelerate the 1,4-heteroaryl migration, which determines the regioselectivity of this transformation.

Electrochemical Decarboxylative Elimination of Carboxylic Acids to Alkenes

An electrochemical strategy for the decarboxylative elimination of carboxylic acids to alkenes at room temperature has been developed. This mild and oxidant-free method provides a green alternative to traditional thermal decarboxylation reactions. Structurally diverse aliphatic carboxylic acids, including biologically active drugs, underwent smooth conversion to the corresponding alkenes in good to excellent yields.

Electrophotochemical Synthesis Facilitated Trifluoromethylation of Arenes Using Trifluoroacetic Acid

The trifluoromethyl (CF3) group is an essential moiety in medicinal chemistry due to its unique physicochemical properties. While trifluoroacetic acid (TFA) is an inexpensive and easily accessible reagent, its use as a source of CF3 is highly challenging due to its high oxidation potential. In this study, we present a novel electrophotochemical approach that enables the use of TFA as the CF3 source for the selective, catalyst- and oxidant-free trifluoromethylation of (hetero)arenes. Key to our approach is the selective oxidation of TFA over arenes, generating CF3 radicals through oxidative decarboxylation. This strategy enables the sustainable and environmentally-friendly synthesis of CF3-, CF2H- and perfluoroalkyl-containing (hetero)arenes with a broad range of substrates. Importantly, our results demonstrate significantly improved chemoselectivity by light irradiation, opening up new possibilities for the synthetic and medicinal applications of TFA as an ideal yet underutilized CF3 source.

Current State of Microflow Trifluoromethylation Reactions

The trifluoromethyl group is a powerful structural motif in drugs and polymers; thus, developing trifluoromethylation reactions is an important area of research in organic chemistry. Over the past few decades, significant progress has been made in developing new methods for the trifluoromethylation of organic molecules, ranging from nucleophilic and electrophilic approaches to transition-metal catalysis, photocatalysis, and electrolytic reactions. While these reactions were initially developed in batch systems, more recent microflow versions are highly attractive for industrial applications owing to their scalability, safety, and time efficiency. In this review, we discuss the current state of microflow trifluoromethylation. Approaches for microflow trifluoromethylation based on different trifluoromethylation reagents are described, including continuous flow, flow photochemical, microfluidic electrochemical reactions, and large-scale microflow reactions.

Understanding and Controlling Fluorinated Diacyl Peroxides and Fluoroalkyl Radicals in Alkene Fluoroalkylations

The demand for practical methods for the synthesis of novel fluoroalkyl molecules is increasing owing to their diverse applications. Our group has achieved efficient difunctionalizing fluoroalkylations of alkenes using fluorinated carboxylic anhydrides as user-friendly fluoroalkyl sources. Fluorinated diacyl peroxide, prepared in situ from carboxylic anhydrides, enables the development of novel reactions when used as a radical fluoroalkylating reagent. In this account, we aim to provide an in-depth understanding of the structure, bonding, and reactivity of fluorinated diacyl peroxides and radicals as well as their control in fluoroalkylation reactions. In the first part of this account, the physical properties and reactivity of diacyl peroxides and fluoroalkyl radicals are described. In the subsequent part, we categorize the reactions into copper-catalyzed and metal-free methods utilizing the oxidizing properties of fluorinated diacyl peroxides. We also outline examples and mechanisms.

Visible-Light-Promoted Decarboxylative Alkylation/Cyclization of Vinylcycloalkanes

An efficient strategy for visible-light-promoted decarboxylative alkylation of vinylcyclopropanes with alkyl N-(acyloxy)phthalimide esters through the dual C-C bond and single N-O bond cleavage, employing triphenylphosphine and lithium iodide as the photoredox system to synthesize 2-alkylated 3,4-dihydronaphthalenes, has been established. This alkylation/cyclization involves a radical process and undergoes a sequence of N-(acyloxy)phthalimide ester single-electron reduction, N-O bond cleavage, decarboxylative, alkyl radical addition, C-C bond cleavage, and intramolecular cyclization. Moreover, using the photocatalyst Na₂-Eosin Y instead of triphenylphosphine and lithium iodide, the vinyl transfer products are acquired when vinylcyclobutanes or vinylcyclopentanes are utilized as alkyl radical receptors.

Metal-free highly chemo-selective bisphosphorylation and deoxyphosphorylation of carboxylic acids

Carboxylic acids are readily available in both the natural and synthetic world. Their direct utilization for preparing organophosphorus compounds would greatly benefit the development of organophosphorus chemistry. In this manuscript, we describe a novel and practical phosphorylating reaction under transition metal-free reaction conditions that can selectively convert carboxylic acids into the P-C-O-P motif-containing compounds through bisphosphorylation, and the benzyl phosphorus compounds through deoxyphosphorylation. This strategy provides a new route for carboxylic acid conversion as the alkyl source, enabling highly efficient and practical synthesis of the corresponding value-added organophosphorus compounds with high chemo-selectivity and wide substrate scope, including the late modification of complex APIs (active pharmaceutical ingredients). Moreover, this reaction also indicates a new strategy for converting carboxylic acids into alkenes by coupling this work and the subsequent WHE reaction with ketones and aldehydes. We anticipate that this new mode of transforming carboxylic acids will find wide application in chemical synthesis.

Catalytic Decarboxylative Radical Sulfinylation

Sulfoxides are ubiquitous in both naturally and synthetically bioactive molecules. We report herein a redox-neutral and mild approach for radical sulfinylation of redox-active esters via dual photoredox and copper catalysis, furnishing a series of functionalized sulfoxides. The reaction could accommodate a range of tertiary, secondary, and primary carboxylic acids, as well as exhibit wide functional group compatibility. The chemistry features a high degree of practicality, is scalable, and allows late-stage modification of bioactive pharmaceuticals.

Merging Copper(I) Photoredox Catalysis and Iodine(III) Chemistry for the Oxy-monofluoromethylation of Alkenes

A simple process for the oxy-monofluoromethylation of alkenes is described. In combination with visible-light copper(I) photoredox catalysis, an easily accessible iodine(III) reagent containing monofluoroacetoxy ligands serves as a powerful source of a monofluoromethyl (CH₂ F) radical, enabling the step economical synthesis of γ-fluoro-acetates from a broad range of olefinic substrates under mild conditions. Applications to late-stage diversification of alkenes derived from complex molecules, amino acids and the synthesis of fluoromethylated heterocycles are also demonstrated.

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.

Synthesis of Optically Active Organofluorides by Ring Opening of Oxazolidinone-Fused Aziridines

A general method for synthesizing optically active, primary, secondary, and tertiary organofluorides was developed. This chiral pool synthesis utilized the skeleton of arabinose to generate diastereomerically pure 2-oxazolidinone-fused aziridines, which underwent ring opening with a fluoride anion. The adducts, polyoxygenated organofluorides, were useful precursors to various fluorinated compounds, such as fluorinated amino acids.

Catalytic and Chemodivergent Synthesis of 1-Substituted 9H-Pyrrolo[1,2-a]indoles via Annulation of β-CF3 Enones with 3-Substituted Indoles

Chemodivergent reactions are more advantageous in organic synthesis that yield diversely functionalized scaffolds from common starting materials. Herein, we report an efficient metal-free chemodivergent protocol for the synthesis of 1-substituted 9H-pyrrolo[1,2-a]indole derivatives in the presence of catalytic amounts of Lewis acid/Brønsted acid conditions using 3-substituted indoles and β-trifluoromethyl-α,β-unsaturated ketones. Fine-tuning of the catalyst and solvent system in the reaction conditions deliver the trifluoromethyl, trifluoroethylcarboxylate, or carboxylic acid substituents on the C1-position of 9H-pyrrolo[1,2-a]indole derivatives in situ. It is postulated that the solvent and LA/BA catalyst interaction was found to be crucial for the catalytic C-F activation in these transformations.

Direct fluoroalkylthiolation of indoles with iodofluoroethane enabled by Na2S2O4

In this paper, we report an efficient approach for the direct fluoroalkylthiolation of indoles with iodofluoroethane in the presence of Na₂S₂O₄. In this work, we employed readily available iodofluoroethane and Na₂S₂O₄ as fluoroalkylthiolation reagents, featuring mild conditions and a wide range of indole substrates. In addition, fluoroalkylthiolated 2,3'-biindole derivatives can also be prepared by this method.

Organophotoredox and Hydrogen Atom Transfer Cocatalyzed C-H Alkylation of Quinoxalin-2(1H)-ones with Aldehydes, Amides, Alcohols, Ethers, or Cycloalkanes

Described is a mild method that merges organophotoredox catalysis with hydrogen atom transfer to enable C-H alkylation of quinoxalin-2(1H)-ones with feedstock aldehydes, amides, alcohols, ethers, or cycloalkanes. This reaction occurred under environmentally benign and external oxidant-free reaction conditions, providing a general and sustainable access to various C3-alkylated quinoxalinone derivatives with broad substituent diversity and good functional group compatibility.

Access to quinolinones via DMAP-catalysed cascade reaction of 2-substituted benzoic acids with organic azides

Herein, we report a DMAP-catalysed Curtius rearrangement and intramolecular cyclisation cascade reaction of 2-substituted aryl carboxylic acids with organic azides for the first time. This protocol features simple operation, broad scope and metal-free conditions, furnishing a broad spectrum of biologically attractive heterocycles. The synthetic virtue of this reaction was demonstrated by gram-scale synthesis and applicability toward drug-like molecules.

Cobalt-catalyzed synthesis of aryl ketones and aldehydes from redox-active esters

A cobalt-catalyzed decarboxylative oxidation of benzylic redox-active esters is described. This protocol efficiently converts secondary or primary aliphatic carboxylic acids into aromatic ketones or aldehydes. A wide range of substrates selectively reacted in good to excellent yields with broad functional group tolerance. Notably, various biologically active molecules could also work well, which indicated the synthetic application of such a methodology.

Visible-Light-Induced Decarboxylative Fluorination of Aliphatic Carboxylic Acids Catalyzed by Iron

An efficient and inexpensive protocol for the direct decarboxylative fluorination of aliphatic carboxylic acids catalyzed with iron salts under visible light is presented. This new method allows the facile fluorination of a diverse array of carboxylic acids even on gram scale using a Schlenk flask without loss of efficiency. Mechanistic studies suggest that the photoinduced ligand-to-metal charge transfer process enables the generation of the key step to generate the carboxyl radical intermediates.

Benzylic Fluorination Induced by a Charge-Transfer Complex with a Solvent-Dependent Selectivity Switch

We present a divergent strategy for the fluorination of phenylacetic acid derivatives that is induced by a charge-transfer complex between Selectfluor and 4-(dimethylamino)pyridine. A comprehensive investigation of the conditions revealed a critical role of the solvent on the reaction outcome. In the presence of water, decarboxylative fluorination through a single-electron oxidation is dominant. Non-aqueous conditions result in the clean formation of α-fluoro-α-arylcarboxylic acids.

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.

Photochemical and Electrochemical Strategies for Hydrodefluorination of Fluorinated Organic Compounds

Hydrodefluorination (HDF) is a very important fundamental transformation for conversion of the C-F bond into the C-H bond in organic synthesis. In the past decade, much progress has been achieved with HDF through the utility of low-valent metals, transition-metal complexes and main-group Lewis acids. Recently, novel methods have been introduced for this purpose through photo- and electrochemical pathways, which are of great significance, due to their considerable environmental and economical advantages. This Review highlights the HDF of fluorinated organic compounds (FOCs) through photo- and electrochemical strategies, along with mechanistic insights.

Fluorinated Nucleosides: Synthesis, Modulation in Conformation and Therapeutic Application

Over the last twenty years, fluorination on nucleoside has established itself as the most promising tool to use to get biologically active compounds that could sustain the clinical trial by affecting the pharmacodynamics and pharmacokinetic properties. Due to fluorine's inherent unique properties and its judicious introduction into the molecule, makes the corresponding nucleoside metabolically very stable, lipophilic, and opens a new site of intermolecular binding. Fluorination on various nucleosides has been extensively studied as a result, a series of fluorinated nucleosides come up for different therapeutic uses which are either approved by the FDA or under the advanced stage of the clinical trial. Here in this review, we are summarizing the latest development in the chemistry of fluorination on nucleoside that led to varieties of new analogs like carbocyclic, acyclic, and conformationally biased nucleoside and their biological properties, the influence of fluorine on conformation, oligonucleotide stability, and their use in therapeutics.

Silver-catalyzed monofluoroalkylation of heteroarenes with α-fluorocarboxylic acids: an insight into the solvent effect

A mild and efficient method for direct C-H monofluoroalkylation of heteroarenes with easily accessible and inexpensive α-fluorocarboxylic acids has been developed. This silver-catalyzed reaction affords mono- and bis-monofluoroalkylated heteroarenes in good yields under mild conditions, and the solvent effect on the monofluoroalkylation reaction is discussed in detail.

Access to gem-Difluoroalkenes via Organic Photoredox-Catalyzed gem-Difluoroallylation of Alkyl Iodides

An organic photoredox-catalyzed gem-difluoroallylation of α-trifluoromethyl alkenes with alkyl iodides via C-F bond cleavage for the synthesis of gem-difluoroalkene derivatives is reported. This transition-metal-free transformation utilized a readily available organic dye 4CzIPN as the sole photocatalyst and employed a common chemical N,N,N',N'-tetramethylethylenediamine as the radical activator of alkyl iodides via halogen-atom transfer. In addition, a variety of iodides, including primary, secondary, and tertiary alkyl iodides, were tolerated and provided good to high yields.