Palladium-Catalyzed Amide Synthesis via Aminocarbonylation of Arylboronic Acids with Nitroarenes

Photocatalytic Approach Toward the Synthesis of Amides via S-C Cleavage: A Mild Approach

A metal-free photocatalytic methodology for the synthesis of amides has been developed using eosin Y as a photocatalyst under ambient conditions. This approach provides a sustainable and efficient alternative for amide formation by eliminating the need for metal catalysts, and operates efficiently at room temperature. The use of eosin Y promotes high selectivity and reactivity, providing a green and cost-effective pathway for the synthesis of amides.

Nickel-Catalyzed Gas-Free Reductive Carbonylation of Aryl Thianthrenium Salts to Access Aryl Amides and Aryl Thioesters

A nickel-catalyzed site-selective reductive carbonylation of arenes via aryl thianthrenium salts is described. Using Mo(CO)6 as a convenient solid CO source and reductant and employing nitroarenes and sulfonyl chlorides as readily available nitrogen and sulfur sources, a range of aryl amides and aryl thioesters were successfully synthesized in moderate to good yields. The utility of this transformation is demonstrated through the synthesis of antimicrobial agents and the late-stage functionalization of biorelevant molecules.

Mo-Mediated Reductive Cyclization/Allylation of 2-Alkynyl Nitroarenes with 1,3-Dienes: Synthesis of 3-Allylindoles

3-Allylindoles constitute a key structural feature in many natural products and bioactive compounds. In this work, we developed a Mo-mediated reductive cyclization/allylation of 2-alkynyl nitroarenes with 1,3-dienes. Using Mo(CO)6 as both the reductant and the catalyst, a broad range of functionalized 3-allylindoles were prepared in good to excellent yields from easily available 2-alkynylnitroarenes and 1,3-dienes as starting materials.

Iron-Assisted and Cu-Mediated Direct Aminocarbonylation of Nitroarene with Boronic Acid

Herein, we have established the formation of diaryl amide by aminocarbonylation of nitrobenzene with boronic acids. The method works in the catalytic presence of economical and commercially available CuI salt, which was significantly promoted by the Fe3Se2(CO)9 cluster. Mo(CO)6 serves as a source of CO, and it also acts as a reductant with a combination of iron cluster. Moreover, all the reaction worked under the ligand-free system and produced the desired diaryl amide in a significant time of 10 h. Water, a green solvent, was used as a source of hydrogen for the reduction of nitrobenzene to aniline. The method depicts a suitable functional group tolerance and produces a wide range of substrates in good to excellent amounts. To the best of our knowledge, this is the first report for the direct aminocarbonylation mediated by highly economical CuI. Moreover, water as a source of hydrogen for the reduction of nitroarene is always appreciated.

Aminocarbonylation using CO surrogates

Aminocarbonylation reactions play a critical role in the synthesis of amides. Traditional aminocarbonylation processes often rely on carbon monoxide (CO) gas, a highly toxic and challenging reagent to handle. Recent advancements in CO surrogates address these challenges. This review looks at the various CO substitutes used in aminocarbonylation reactions. These include metal carbonyls, acids, formates, chloroform, and others that release CO. Use of CO surrogates not only improves safety but also broadens the substrate scope and operational simplicity of the aminocarbonylation reactions. This review provides a summary of recent progress made in aminocarbonylation reactions using different CO surrogates. We discuss key methodologies, catalytic systems, and mechanistic insights, highlighting the efficiency and versatility of CO surrogates in amide bond formation.

Molybdenum-Mediated Reductive ortho-Alkylation of Nitroarenes with Alcohols

A molybdenum-mediated reductive ortho-alkylation of nitroarenes with alcohols for the synthesis of ortho-alkylated anilines has been developed. Using Mo(CO)6 as both the reductant and the catalyst, a range of ortho-alkyl-substituted anilines were prepared from nitroarenes and alcohols. Preliminary mechanistic studies indicate that nitroarenes were reduced by Mo(CO)6 to aniline in the presence of H2O, while an oxidized Mo species catalyzed the alkylation portion of this reaction.

CuH-Catalyzed Reductive Coupling of Nitroarenes with Phosphine Oxides for the Direct Synthesis of Phosphamides

A CuH-catalyzed reductive coupling of nitroarenes with phosphine oxides is developed, which produces a series of phosphamides in moderate to excellent yields with good functional group tolerance. Gram-scale synthesis and late-stage modification of nitro-aromatic functional molecule niclosamide are also successfully conducted. The mechanism study shows that the nitro group is transformed after being reduced to nitroso and a nucleophilic addition procedure is involved during the reaction.

Electrochemical Oxidative Carbonylation of NH-Sulfoximines

The electrochemical synthesis of N-aroylsulfoximines features the use of tetra-n-butylammonium iodide (TBAI) as the medium and a broad substrate scope, thus affording a wide range of N-aroylated sulfoximines in moderate to good yields. The advantages of this electrochemical strategy are augmented by mild reaction conditions that are external oxidant-free, ligand-free, and easy to scale up to gram scale. Both the control experiments and the mechanistic studies revealed that the whole electrochemical process proceeded through a palladium (II/IV/II) catalytic cycle.

Molybdenum-Mediated Reductive Hydroamination of Vinylcyclopropanes with Nitroarenes: Synthesis of Homoallylamines

A molybdenum-mediated reductive hydroamination of vinylcyclopropanes with nitroarenes has been developed. A broad range of substituted homoallylamines were prepared in good to excellent yields from readily available starting materials. No noble metal catalysts were used in this reaction, and Mo(CO)₆ acted as both catalyst and reductant. This protocol provides an effective method for the selective synthesis of substituted homoallylamines from easily available nitroarenes.

Palladium-Catalysed Reductive Aminocarbonylation of Aryl Bromides and Iodides with Nitroarenes

Amide functional groups are a structural feature in a vast array of beneficial organic molecules. This has resulted in a surge in new methodologies developed to enable access to this functional group using a broad range of coupling partners. Herein, we report a palladium-catalysed reductive aminocarbonylation of aryl bromides and iodides with nitroarenes to afford the respective amide products. The developed protocol employs Mo(CO)6 as a carbonyl source and a combination of Zn and TMSCl as co-reducing agents. For most substrates, the anticipated amide products were obtained in modest to high amide product yields.

Palladium-Catalyzed Intramolecular Heck/Aminocarbonylation of Alkene-Tethered Iodobenzenes with Nitro Compounds: Synthesis of Carbamoyl-Substituted Benzoheterocycles

A palladium-catalyzed intramolecular Heck/aminocarbonylation of alkene-tethered iodobenzenes with nitro compounds has been developed for the synthesis of carbamoyl-substituted benzoheterocycles. Using Mo(CO)₆ as a solid CO source, no external reductant or additives were needed in this procedure. Both nitroarenes and nitroalkanes were well tolerated. A range of carbamoyl-substituted dihydrobenzofurans and indolines were prepared in moderate to high yields.

Plasma flow chemistry for direct N-acylation of amines by esters

The direct N-acylation of amines by esters in a microreactor is described using argon plasma, thereby producing amides in good to excellent yields.

Copper-promoted cross-coupling of nitroarenes with 4-alkyl-1,4-dihydropyridines using a peroxide-driven radical reductive strategy

Direct radical-mediated reductive coupling of nitroarenes with 4-alkyl-1,4-dihydropyridines to build the C(sp3)–N bond using 4-alkyl-1,4-dihydropyridines as internal reducing agents and alkyl sources is presented.

Palladium-catalyzed carbonylative synthesis of indole-3-carboxamides from 2-ethynylanilines and nitroarenes

A facile and straightforward approach for the expedite construction of indole-3-carboxamide skeletons via a palladium-catalyzed carbonylative cyclization of 2-ethynylanilines with nitroarenes has been developed.

Nickel-catalyzed carbonylative domino cyclization of arylboronic acid pinacol esters with 2-alkynyl nitroarenes toward N-aroyl indoles

A nickel-catalyzed carbonylative domino cyclization of arylboronic acid pinacol esters with 2-alkynyl nitroarenes has been developed.

Mo-Catalyzed One-Pot Synthesis of N-Polyheterocycles from Nitroarenes and Glycols with Recycling of the Waste Reduction Byproduct. Substituent-Tuned Photophysical Properties

A catalytic domino reduction-imine formation-intramolecular cyclization-oxidation for the general synthesis of a wide variety of biologically relevant N-polyheterocycles, such as quinoxaline- and quinoline-fused derivatives, and phenanthridines, is reported. A simple, easily available, and environmentally friendly dioxomolybdenum(VI) complex has proven to be a highly efficient and versatile catalyst for transforming a broad range of starting nitroarenes involving several redox processes. Not only is this a sustainable, step-economical as well as air- and moisture-tolerant method, but also it is worth highlighting that the waste byproduct generated in the first step of the sequence is recycled and incorporated in the final target molecule, improving the overall synthetic efficiency. Moreover, selected indoloquinoxalines have been photophysically characterized in cyclohexane and toluene with exceptional fluorescence quantum yields above 0.7 for the alkyl derivatives.

Direct Access to Amides from Nitro-Compounds via Aminocarbonylation and Amidation Reactions: A Minireview

The ubiquity of the amide bond in functional molecules including proteins, natural products, pharmaceuticals, agrochemicals and materials provides impetus to design and develop newer strategies for the generation of this linkage. Owing to growing awareness about sustainability and development of benign strategies, the traditional route of synthesis of amides via reaction between carboxylic acids and amines in the presence of stoichiometric amount of coupling reagents is tagged to be harsh and wasteful. In one of the unconventional routes, nitro compounds are used directly as amine surrogates for preparing amides mostly via aminocarbonylation and amidation reactions. Typically, such processes involves nitroarenes owing to their propensity to transform into nitroso, hydroxylamine, diazo, hydrazine or aniline intermediates in situ under the influence of suitable catalyst or oxidant. This short review provides the comprehensive overview of these reactions including insight into the scope and their mechanisms.

UV-Light-Induced N-Acylation of Amines with α-Diketones

Herein, we develop a mild method for N-acylation of primary and secondary amines with α-diketones induced by ultraviolet (UV) light. Forty-six examples with various functional groups are explored at room temperature with irradiation by three 26 W UV lamps (350-380 nm). The yield reaches 97%. The gram scale experiment product yield is 76%. Moreover, this system can be applied to the synthesis of several amino acid derivatives. Mechanistic studies show that benzoin is generated in situ from benzil under UV irradiation.

Organocatalytic aminocarbonylation of α,β-unsaturated ketones with N,N-dimethyl carbamoylsilane

Schwesinger's superbase can efficiently activate the Si–CONMe₂ bond and initiate the aminocarbonylation of α,β-unsaturated ketones and N,N-dimethyl carbamoylsilane.

Tandem Synthesis of 2-Carboxybenzofurans via Sequential Cu-Catalyzed C-O Coupling and Mo(CO)6-Mediated Carbonylation Reactions

A modular tandem synthesis of 2-carboxybenzofurans from 2-gem-dibromovinylphenols has been established based on a sequence of Cu-catalyzed intramolecular C-O coupling and Mo(CO)₆-mediated intermolecular carbonylation reactions. This protocol allowed one-step access to a broad variety of functionalized benzofuran-2-carboxylic acids, esters, and amides in good to excellent yields under Pd- and CO gas-free conditions.

Direct N-formylation of nitroarenes with CO2

Herein we describe a straightforward N-formylation of nitroarenes with CO₂ to access N-aryl formamides exclusively in the presence of iron and hydrosilane as additives. This protocol showcases a good tolerance of a wide range of nitroarenes and nitroheteroarenes.

New Efficient Eco-Friendly Supported Catalysts for the Synthesis of Amides with Antioxidant and Anti-Inflammatory Properties

A new environmentally friendly approach for the synthesis of idrocilamide (1), a marketed myorelaxant and anti-inflammatory agent, is reported herein. The synthetic strategy involves a solvent-free aminolysis reaction catalyzed by zinc-containing species (ZnCl₂ , montmorillonite K10 (MK10) impregnated with ZnCl₂ or eco-catalysts). The latter have been prepared from the aerial parts of Lolium perenne L. plants grown on contaminated soils from northern France without and with thermal activation at 120 °C and supported on MK10 (Ecocat1 and Ecocat2, respectively). The best aminolysis catalysts in the current study (ZnCl₂ and Ecocat2) were selected for additional aminolyses. Compared to ZnCl₂ , Ecocat2 had the advantage of being reusable over five test runs and constituted a sustainable catalyst allowing a green route to idrocilamide. Synthesized derivatives 1-4, 6 and 9 were first evaluated for their effect on reactive oxygen species (ROS) generation from macrophages and displayed antioxidant properties by preventing ROS production. Next, the analysis of the effect of molecules 1-4, 6 and 9 on macrophage migration between epithelial cells to human opportunistic fungus Candida albicans indicated that molecules 2-4, 6 and 9 exert anti-inflammatory properties via reducing macrophage migration while the parent idrocilamide (1) did not show any significant effect. This work opens the way for the discovery of new analogues of idrocilamide with improved properties.

Direct amide synthesis via Ni-mediated aminocarbonylation of arylboronic acids with CO and nitroarenes

Ni metal-mediated aminocarbonylation based on readily available arylboronic acids, nitroarenes, and carbon monoxide was achieved to prepare a variety of aryl amides.