General Method for Selective Three-Component Carboacylation of Alkenes via Visible-Light Dual Photoredox/Nickel Catalysis

Nickel/Photoredox Dual-Catalyzed, Regioselective 1,2-Carboacylation of Alkenes via Synergistic Alkyl and Benzoyl Radical Coupling

A regioselective 1,2-carboacylation protocol of alkenes via nickel/photoredox dual catalysis has been successfully developed under mild conditions. A wide range of alkyl bromides, α-oxocarboxylic acids, and styrenes proved to be compatible under the optimized conditions, affording the corresponding 1,2-carboacylation products in up to 91% yields. Mechanistically, the key to the success of this approach is the temporal orchestration of radical generation: nickel-catalyzed halogen atom transfer (XAT) for alkyl bromides and photoredox-driven decarboxylation for α-oxocarboxylic acids.

Three-Component 1,2-Carboalkynylation of Alkenes Via Cooperative Nickel/Photoredox Catalysis

A photoredox/nickel dual catalytic system was developed for the three-component 1,2-carboalkynylation of alkenes. This redox-neutral protocol enables the efficient and divergent synthesis of aliphatic alkynes in high yields with excellent regioselectivity, using readily available starting materials. The resulting adducts can be readily transformed into terminal alkynes, facilitating diverse downstream transformations. Mechanistic studies were performed to elucidate the preferred pathway of this alkene difunctionalization process.

Direct alkene functionalization via photocatalytic hydrogen atom transfer from C(sp3)-H compounds: a route to pharmaceutically important molecules

Direct functionalization of alkenes with C(sp3)-H substrates offers unique opportunities for the rapid construction of pharmaceuticals and natural products. Although significant progress has been made over the past decades, the development of green, high step-economy methods to achieve these transformations under mild conditions without the need for pre-functionalization of C(sp3)-H bonds remains a substantial challenge. Therefore, the pursuit of such methodologies is highly desirable. Recently, the direct activation of C(sp3)-H bonds via photocatalytic hydrogen atom transfer (HAT), especially from unactivated alkanes, has shown great promise. Given the potential of this approach to generate a wide range of pharmaceutically relevant compounds, this review highlights the recent advancements in the direct functionalization of alkenes through photocatalytic HAT from C(sp3)-H compounds, as well as their applications in the synthesis and diversification of drugs, natural products, and bioactive molecules, aiming to provide medicinal chemists with a practical set of tools.

Dual Photoredox/Nickel Catalysis Enables Diastereoselective Synthesis of Multisubstituted γ-Lactams Using Alkyl-GeMe3 as Radical Precursors

Herein, we report a single-step, multicomponent approach to versatile γ-lactams through dual photoredox/nickel-catalyzed dicarbofunctionalization of α,β-unsaturated γ-butyrolactam. This reaction utilized alkyl trimethylgermanium as a radical precursor and acyl chloride as the electrophile, demonstrating remarkable functional group compatibility.

anti-Selective Carboacylation of Alkynes via Photoredox/Nickel Dual Catalysis

Here, we report an intermolecular carboacylation of terminal alkynes with tertiary and secondary alkyltrifluoroborates as well as acyl chlorides via photoredox/nickel dual catalysis, affording a varity of stereodefined trisubstituted enones in good to excellent yields and E stereoselectivity, through a radical relay process. This redox-neutral protocol exhibits excellent functional group tolerance, exclusive regio- and stereoselectivity, and broad compatibility with various acyl chlorides and alkyltrifluoroborates.

Nickel-Catalyzed Three-Component 1,2-Carboacylation of Alkenes

Ketones, prevalent in many biologically significant molecules, require the development of novel methods to synthesize these structures, which is a critical endeavor in organic synthesis. Transition metal catalysis has proven to be an effective method for synthesizing ketones. However, the scope of these substrates remains relatively limited, particularly due to their incompatibility with sensitive functional groups. Herein, we report a Ni-catalyzed three-component 1,2-carboacylation of alkenes, which activates secondary/tertiary alkyl bromides. This method offers significant advantages: simplicity of operation, ready availability of substrates, and broad substrate applicability. A series of experimental studies have helped clarify the key mechanistic pathways involved in this cascade reaction.

Intermolecular Regioselective Alkylarylation of Vinylarenes via Photoredox/Nickel Dual Catalysis

A novel photoredox/nickel dual catalytic intermolecular alkylarylation of vinylarenes with tertiary and secondary alkyltrifluoroborates and aryl bromides is described, which affords 1,1-diarylalkane frameworks that are found in various natural products as well as functionalized molecules in good to excellent yield and regioselectivity through a radical relay process. Notably, this redox-neutral reaction could proceed efficiently with good tolerance of various substrates, including a great diversity of commercially available (hetero)aryl bromides, alkyltrifluoroborates, and vinylarenes.

Recent advances in dual photoredox/nickel catalyzed alkene carbofunctionalised reactions

Alkene carbofunctionalization reactions have great potential for synthesizing complex molecules and constructing complex structures in natural products and medicinal chemistry. Recently, dual photoredox/nickel catalysis has emerged as a novel strategy for alkene carbofunctionalization. Nickel offers numerous advantages over other transition metals, such as cost-effectiveness, abundance, and low toxicity, and moreover, it has many oxidation states. Nickel catalysts exhibit excellent catalytic activity in dual photoredox/transition metal catalysis, facilitating the formation of carbon-carbon or carbon-heteroatom bonds in organic transformations. This review highlights the latest advancements in dual photoredox/nickel-catalyzed alkene carbofunctionalizations and includes the literature published from 2020 to 2024.

Ligand Relay for Nickel-Catalyzed Decarbonylative Alkylation of Aroyl Chlorides

Transition metal-catalyzed direct decarboxylative transformations of aromatic carboxylic acids usually require high temperatures, which limit the substrate's scope, especially for late-stage applications. The development of the selective decarbonylative of carboxylic acid derivatives, especially the most fundamental aroyl chlorides, with stable and cheap electrophiles under mild conditions is highly desirable and meaningful, but remains challenging. Herein, a strategy of nickel-catalyzed decarbonylative alkylation of aroyl chlorides via phosphine/nitrogen ligand relay is reported. The simple phosphine ligand is found essential for the decarbonylation step, while the nitrogen ligand promotes the cross-electrophile coupling. Such a ligand relay system can effectively and orderly carry out the catalytic process at room temperature, utilizing easily available aroyl chlorides as an aryl electrophile for reductive alkylation. This discovery provides a new strategy for direct decarbonylative coupling, features operationally simple, mild conditions, and excellent functional group tolerance. The mild approach is applied to the late-stage methylation of various pharmaceuticals. Extensive experiments are carried out to provide insights into the reaction pathway and support the ligand relay process.

Synthesis of Chiral α-Aryl Ketones by Photoredox/Nickel-Catalyzed Enantioconvergent Acyl Cross-Coupling with Organotrifluoroborate

Photoredox/nickel-catalyzed enantioconvergent acyl cross-coupling of carboxylic derivatives with racemic secondary organotrifluoroborate was developed for the synthesis of an enolizable chiral α-aryl ketone under mild neutral conditions. Moderate to high yields and good enantioselectivities were achieved.

Enantioenriched Allylesters via a Copper-Catalyzed Diene Carboesterification with Alkyltrifluoroborates and Carboxylic Acids

The rapid synthesis of a range of enantioenriched allylic esters is enabled by a new 3-component catalytic enantioselective 1,2-carboesterification of readily available dienes with carboxylic acids and potassium alkyltrifluoroborates. The chiral copper catalyst, formed in situ from Cu(OTf)2 and (4S,4'S)-2,2'-(cyclopentane-1,1-diyl)bis(4-phenyl-4,5-dihydrooxazole), is implicated in both the generation of alkyl radicals from the alkyltrifluoroborates as well as the enantioselective formation of C-O bonds. Potassium salts of primary and secondary alkyltrifluoroborates as well as several benzylic trifluoroborates, tert-butyltrifluoroborate, and phenyltrifluoroborate participate in the reaction. The regioselectivity and enantioselectivity are strongly impacted by variations in all of the reaction components, which in turn are thought to impact the C-O bond-forming reductive elimination from a [Cu(III)] intermediate.

Nickel/Photo-Cocatalyzed Three-Component Alkyl-Acylation of Aryl-Activated Alkenes

Herein, we disclose a nickel/photo-cocatalyzed three-component alkyl-acylation of aryl-substituted alkenes with aldehydes and electron-withdrawing-group-activated alkyl bromides, providing straightforward access to various ketones under mild and ligand-free conditions. The photocatalyst TBADT plays a dual role in activating the acyl C-H bond of aldehydes via hydrogen atom transfer and reducing the C-Br bond of alkyl bromides via single-electron transfer. While the terminal C-C bond is forged through polarity-matched radical-type addition, nickel is likely involved in the acylation step.

Synthesis of α-Branched Enones via Chloroacylation of Terminal Alkenes

Here, we show the conversion of unactivated alkenes into α-branched enones via regioselective chloroacylation with acyl chlorides. The method relies upon the initial in situ generation of chlorine radicals directly from the acyl chloride precursor under cooperative nickel/photoredox catalysis. Subsequent HCl elimination provides enones and α,β-unsaturated esters that are not accessible via the conventional acylation approaches that provide the other, linear constitutional isomer.

Visible Light Induced Three-Component 1,2-Dicarbofunctionalization of Alkenes and Alkynes

Harnessing visible-light in organic synthesis is one of the most effective methods that aligns with green and sustainable chemistry principles and hence skyrocketed in the last two decades. Similarly, three-component 1,2-dicarbofunctionalization of alkenes and alkynes has recently been a great choice to construct complex molecular systems in an easy and rapid manner. Therefore, light-induced reactions can be an excellent alternative to carry out 1,2-dicarbofunctionalization reactions, and very recently, organic chemists across the globe have fascinated us with their interesting articles. In this present review, we have summarized the recent advancements in the area of visible light induced three-component 1,2-dicarbofunctionalization of alkenes and alkynes till March 2023. We have categorized the discussion based on the catalysts used to carry out the transformations for better understanding and different important aspects of these transformations have also been covered.

Visible-Light-Mediated Three-Component Decarboxylative Coupling Reactions to Synthesize 1,4-Diol Monoethers

An efficient approach for 1,2-difunctionalization of aromatic olefins and the synthesis of functionalized 1,4-diols monoethers has been established via a photoinduced three-component reaction of an α-alkoxycarboxylic acid, an aromatic olefin, and an aldehyde. The reaction proceeds by photoinduced oxidative decarboxylation of the carboxylic acid followed by the addition of the α-alkoxyalkyl radical to the olefin, one-electron reduction of the addition radical, and the nucleophilic attack of the resulting carbanion to the aldehyde. Besides the convenient one-pot protocol of the three-component reaction, this method offers several other advantages, including good functional group tolerance for the three substrates, gentle reaction conditions, and ease of scaling up. The reaction mechanism has been investigated through free radical trapping experiment and isotope labeling experiments.

Nickel/Titanocene-Catalyzed Electrophilic Acylation Coupling of Styrene Oxides

The cross-coupling of epoxides with acyl chlorides or anhydrides by a nickel/titanocene dual catalytic system is established. A variety of synthetically useful β-hydroxy ketones were obtained in good to high yields by using modified pyridine-oxazoline ligand. The reaction proceeds via the cooperation of titanocene-catalyzed ring-opening of epoxides and nickel-catalyzed acylation of the benzylic radical intermediate.