Manganese-Dioxide-Catalyzed Trifluoromethylation and Azidation of Styrenyl Olefins via Radical Intermediates

Pyridinium-Masked Enol as a Precursor for Constructing Alpha-Fluoromethyl Ketones

We present herein a pyridinium-masked enol as a versatile platform to produce ketones bearing tri-, di-, and monofluoromethyl in the presence of [Ir(dF(Me)ppy)]2(dtbbpy)]PF6 under blue light (455 nm) irradiation. By simply changing the F-source, α-trifluoromethyl ketones, α-difluoromethyl ketones, and α-monofluoromethyl ketones could be easily prepared in moderate to excellent yields in one step, making it a practical tool for the synthesis of fluorine-containing ketones. In addition, the pyridinium-masked enol could also be extended to the synthesis of sulfonyl ketones. The findings of the present protocol contribute to the arsenal of fluorine chemistry and might have potential applications in the pharmaceutical and agrochemical industries.

Recent advances in the application of Langlois' reagent in olefin difunctionalization

In this review, we summarise the recent applications of Langlois' reagent in the radical-mediated difunctionalization of alkenes. Among the various trifluoromethylation reagents, Langlois' reagent is an exceptional compound, and many important organic transformations have been realized by employing such reagents. Various organic transformations of Langlois' reagent, especially in radical chemistry, have been developed in recent years. This review describes several key activation methods for Langlois' reagent in the difunctionalization of alkenes by showcasing selected cornerstone research areas and related mechanisms to stimulate the interest of readers in promoting the wider development and application of Langlois' reagent.

Fe-catalyzed hydroxytrifluoromethylation of α-(trifluoromethyl)styrenes with CF3SO2Na: facile access to α,β-bistrifluoromethyl tertiary alcohols

A mild and practical Fe-catalyzed hydroxytrifluoromethylation of α-(trifluoromethyl)styrenes with CF₃SO₂Na in the presence of K₂S₂O₈ and air was developed. The reaction proceeded efficiently at room temperature without β-fluoride elimination and afforded the corresponding α,β-bistrifluoromethyl tertiary alcohols in good to excellent yields.

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

α-Azidoketones are valuable and versatile building blocks in the synthesis of various bioactive small molecules. Herein, we describe an environmentally friendly and efficient electrochemical vicinal oxyazidation protocol of α-arylvinyl acetates to afford diverse α-azidoketones in good yields without the use of a stoichiometric amount of chemical oxidant. A range of functionality is shown to be compatible with this transformation, and further applications are demonstrated.

Chemical versatility of azide radical: journey from a transient species to synthetic accessibility in organic transformations

The generation of azide radical (N₃˙) occurs from its precursors primarily via a single electron transfer (SET) process or homolytic cleavage by chemical methods or advanced photoredox/electrochemical methods. This in situ generated transient open-shell species has unique characteristic features that set its reactivity. In the past, the azide radical was widely used for various studies in radiation chemistry as a 1e^- oxidant of biologically important molecules, but now it is being exploited for synthetic applications based on its addition and intermolecular hydrogen atom transfer (HAT) abilities. Due to the significant role of nitrogen-containing molecules in synthesis, drug discovery, biological, and material sciences, the direct addition onto unsaturated bonds for the simultaneous construction of C-N bond with other (C-X) bonds are indeed worth highlighting. Moreover, the ability to generate O- or C-centered radicals by N₃˙ via electron transfer (ET) and intermolecular HAT processes is also well documented. The purpose of controlling the reactivity of this short-lived intermediate in organic transformations drives us to survey: (i) the history of azide radical and its structural properties (thermodynamic, spectroscopic, etc.), (ii) chemical reactivities and kinetics, (iii) methods to produce N₃˙ from various precursors, (iv) several significant azide radical-mediated transformations in the field of functionalization with unsaturated bonds, C-H functionalization via HAT, tandem, and multicomponent reaction with a critical analysis of underlying mechanistic approaches and outcomes, (v) concept of taming the reactivity of azide radicals for potential opportunities, in this review.

Dyedauxiliary Group Strategy for the α-Functionalization of Ketones and Esters

The synthesis of α-arylketones and α-arylazo esters has been achieved in mixed organic-aqueous media under photocatalyst- and metal-free conditions via visible light activation of arylazo sulfones in the presence of enol silyl ethers and ketene silyl acetals, respectively. The process took place efficiently and exhibits an excellent tolerance for a broad variety of functional groups.

Visible-Light-Promoted Regioselective 1,3-Fluoroallylation of gem-Difluorocyclopropanes

A strategically novel protocol for ring-opening functionalization of aryl gem-difluorocyclopropanes (F₂CPs), which allows an expedient construction of CF₃-containing architectures via visible-light-promoted F-nucleophilic attack manifold, was disclosed. Single electron oxidation of F₂CPs was ascribed as the critical step for the success of this transformation by prompting F-nucleophilic attack, as well as the ensuing C-C bond scission. The observed intriguing regioselectivity for fluoroincorporation in this reaction was rationalized by invoking the cation-stabilization property of gem-difluorine substituents and also the thermodynamic gains acquired from forming CF₃ functionality. By using cost-effective fluorination reagent and readily available substrates, a broad collection of structurally diversified α-allyl-β-trifluoromethyl ethylbenzene derivatives could be obtained in generally good yields. Further mechanistic investigations proved the engagement of a benzylic radical intermediate in this transformation.

Bond-Forming and -Breaking Reactions at Sulfur(IV): Sulfoxides, Sulfonium Salts, Sulfur Ylides, and Sulfinate Salts

Organosulfur compounds have long played a vital role in organic chemistry and in the development of novel chemical structures and architectures. Prominent among these organosulfur compounds are those involving a sulfur(IV) center, which have been the subject of countless investigations over more than a hundred years. In addition to a long list of textbook sulfur-based reactions, there has been a sustained interest in the chemistry of organosulfur(IV) compounds in recent years. Of particular interest within organosulfur chemistry is the ease with which the synthetic chemist can effect a wide range of transformations through either bond formation or bond cleavage at sulfur. This review aims to cover the developments of the past decade in the chemistry of organic sulfur(IV) molecules and provide insight into both the wide range of reactions which critically rely on this versatile element and the diverse scaffolds that can thereby be synthesized.

Visible-light promoted sulfonamidation of enol acetates to α-amino ketones based on redox-neutral photocatalysis

A visible-light mediated photoredox-catalyzed sulfonamidation of enol acetates to α-amino ketones has been developed. The process features mild and operationally simple reaction conditions and does not require an external oxidant.

Trifluoromethylation of α-diazoesters and α-diazoketones with fluoroform-derived CuCF3: synergistic effects of co-solvent and pyridine as a promoter

Fluoroform-derived CuCF₃ can efficiently trifluoromethylate α-diazoesters and α-diazoketones. The key is the use of co-solvent and pyridine as a promoter.

Transition metal-free synthesis of fluoroalkylated oxindoles via base-mediated fluoroalkylation of N-arylacrylamides with RFI

A novel method for synthesizing fluoroalkylated oxindoles by the cyclization of N-arylacrylamides with fluoroalkyl iodide initiated with K₂CO₃ is reported.