Search

In order to specifically demonstrate the improvement of photocatalytic activity attributed to the donor‐acceptor (D‐A) structure rather than other contributing factors, two highly comparable COFs incorporating porphyrin and thiophene species are synthesized in this work. The first COF, named BTDA‐Por, is composed of porphyrin (Por) as the donor unit and 2,2′‐bithiophene (BTDA) as the acceptor moiety. The second COF, referred to as TT‐Por, is constructed using Por and thieno[3,2‐b]thiophene (TT) units while lacking a D‐A structure. These synthesized COFs serve as effective models for investigating the role of D‐A structures in improving photocatalytic activity. Photoelectronic property studies and density function theory calculations indicate that the D‐A configuration can significantly enhance the efficiency of charge carrier generation, separation, and migration. Consequently, the D‐A type BTDA‐Por exhibits superior performance in photochemical reactions such as oxidative homocoupling of aromatic amine and reversible complexation‐mediated radical polymerization when compared to the non‐D‐A type TT‐Por. [ABSTRACT FROM AUTHOR]

The utilization of two‐component systems comprising camphorquinone (CQ) and aromatic amines has become prevalent in the photopolymerization. However, there are still concerns about the safety of this CQ/amine system, mainly because of the toxicity associated with the leaching of aromatic amines. In light of these concerns, this study aims to develop novel coinitiator combinations featuring CQ and amines which cannot be leached out of materials, enabling free radical polymerization of representative dentalmethacrylate resins under blue light irradiation. This approach involves the initial design and analysis of hydrogen donors with low C─H bond dissociation energy through molecular modeling. Subsequently, copolymerizable methacrylate functional groups are incorporated via chemical modification, allowing it to act as both coinitiator and copolymerization monomer to achieve low migrationand leachability properties. This work presents, for the first time, the synthesis of the innovative coinitiator and compares its performance with the benchmark CQ/ethyl‐4‐dimethylaminobenzoate (EDB)‐based photoinitiation system (PIS). The results demonstrate the effectiveness of the newly proposed PIS. Finally, an in‐depth investigation is conducted into the reaction mechanism associated with this PIS through molecular orbital calculations and electron spin resonance studies. [ABSTRACT FROM AUTHOR]

Aromatic amines are important commercial chemicals, but their carcinogenicity poses a threat to humans and other organisms, making their rapid quantitative detection increasingly urgent. Here, amorphous MoO3 (a‐MoO3) monolayers with localized surface plasmon resonance (LSPR) effect in the visible region are designed for the trace detection of carcinogenic aromatic amine molecules. The hot‐electron fast decay component of a‐MoO3 decreases from 301 fs to 150 fs after absorption with methyl orange (MO) molecules, indicating the plasmon‐induced hot‐electron transfer (PIHET) process from a‐MoO3 to MO. Therefore, a‐MoO3 monolayers present high SERS performance due to the synergistic effect of electromagnetic enhancement (EM) and PIHET, proposing the EM‐PIHET synergistic mechanism in a‐MoO3. In addition, a‐MoO3 possesses higher electron delocalization and electronic state density than crystal MoO3 (c‐MoO3), which is conducive to the PIHET. The limit of detection (LOD) for o‐aminoazotoluene (o‐AAT) is 10−9 M with good uniformity, acid resistance, and thermal stability. In this work, trace detection and identification of various carcinogenic aromatic amines based on a‐MoO3 monolayers is realized, which is of great significance for reducing cancer infection rates. [ABSTRACT FROM AUTHOR]

Singlet oxygen is a powerful oxidant used in various applications, such as organic synthesis, medicine, and environmental remediation. Organic and inorganic photosensitizers are commonly used to generate this reactive species through energy transfer with the triplet ground state of oxygen. We describe here a series of novel benzophenazine derivatives as a promising class of photosensitizers for singlet oxygen photosensitization. In this study, we investigated the structure‐activity relationship of these benzophenazine derivatives. Akin to a molecular compass, the southern fragment was first functionalized with either aromatic tertiary amines, alkyl tertiary amines, aromatic sulfur groups, alkyl sulfur groups, or cyclic ethers. Enhanced photophysical properties (in terms of triplet excited‐state lifetime, absorption wavelength, triplet state energy, and O2 quenching capabilities) were obtained with cyclic ether and sulfur groups. Conversely, the presence of an amine moiety was detrimental to the photocatalysts. The western and northern fragments were also investigated and slightly undesirable to negligible changes in photophysical properties were observed. The most promising candidate was then immobilized on silica nanoparticles and its photoactivity was evaluated in the citronellol photooxidation reaction. A high NMR yield of 97 % in desired product was obtained, with only a slight decrease over several recycling runs (85 % in the fourth run). These results provide insights into the design of efficient photosensitizers for singlet oxygen generation and the development of heterogeneous systems. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Herein, we present a method for the homogeneous hydrogenation of nitroarenes to produce anilines using low catalyst loading (1 mo%) of copper N‐heterocyclic carbene complexes as the catalyst and ammonia borane as the source of hydrogen. A wide range of nitroarenes, featuring diverse functional groups, were selectively transformed into their corresponding primary aromatic amines with high yields. This process can be readily scaled up and exhibits compatibility with various sensitive functional groups, including halogen, trifluoromethyl, aminomethyl, alkenyl, cyano, ester, amide, and hydroxyl. Notably, this catalytic methodology finds application in the synthesis of essential drug compounds. Mechanistic investigations suggest that the in‐situ‐generated Cu‐H species may serve as active intermediates, with reduction pathways involving species such as azobenzene, 1,2‐diphenylhydrazine, nitrosobenzene, and N‐phenylhydroxylamine. [ABSTRACT FROM AUTHOR]

BACKGROUND: The present research was conducted to investigate the impact of reishi mushroom extract (RME) on the formation of heterocyclic aromatic amines (HAAs) in meatballs. Sample preparations involved applying RME using either the spreading or addition method, with varying concentrations (0%, 0.25%, 0.5%, and 1% of RME), followed by deep‐frying at temperatures of 150 and 190 °C for 3 min. RESULTS: The types and levels of HAAs varied based on the frying temperature, method of extract application, and the extract concentration. Notably, total HAA contents increased with rising the frying temperature (P < 0.01) and varied from undetectable levels to 4.91 ng g−1 across all analyzed meatballs. The addition method was more effective than the spreading method (P < 0.01), and among the concentrations tested 0.25% RME exhibited the highest efficacy in reducing total HAAs (P < 0.05). Furthermore, the addition method inhibited lipid oxidation more efficiently compared to the surface spreading method (P < 0.05). CONCLUSION: This study demonstrated that RME had mitigating effects on HAAs depending on the concentration and frying conditions in deep‐fried meatball samples. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Atropisomers hold significant fascination, not only for their prevalence in natural compounds but also for their biological importance and wide‐ranging applications as chiral materials, ligands, and organocatalysts. While biaryl and heterobiaryl atropisomers are commonly studied, the enantioselective synthesis of less abundant heteroatom‐linked non‐biaryl atropisomers presents a formidable challenge in modern organic synthesis. Unlike classical atropisomers, these molecules allow rotation around two bonds, resulting in low barriers to enantiomerization through concerted bond rotations. In recent years the discovery of new configurationally stable rare non‐biaryl scaffolds such as aryl amines, aryl ethers and aryl sulfones as well as innovative methodologies to control their configuration have been disclosed in the literature and constitute the topic of this minireview. [ABSTRACT FROM AUTHOR]

Biocatalysis provides an attractive approach to facilitate synthetic reactions in aqueous media. Motivated by the discovery of promiscuous aminolysis activity of esterases, we exploited the esterase from Pyrobaculum calidifontis VA1 (PestE) for the synthesis of carbamates from different aliphatic, aromatic, and arylaliphatic amines and a set of carbonates such as dimethyl‐, dibenzyl‐, or diallyl carbonate. Thus, aniline and benzylamine derivatives, aliphatic and even secondary amines could be efficiently converted into the corresponding benzyloxycarbonyl (Cbz)‐ or allyloxycarbonyl (Alloc)‐protected products in bulk water, with (isolated) yields of up to 99 %. [ABSTRACT FROM AUTHOR]

A copper‐catalyzed one‐pot three‐component aminophosphinoylation reaction of 1,4‐naphthoquinone with disubstituted phosphine oxides and arylamines has been developed. Various disubstituted phosphine oxides and arylamines with diverse structures and electronic properties can work smoothly with 1,4‐naphthoquinone, afforded a series of corresponding aminophosphinoylated 1,4‐naphthoquinones with up to 96 % isolated yield. The present method features easily available reagents, operational simplicity, broad substrate scope, high atom and step economy. The potential practicality of this protocol was further demonstrated by gram‐scale synthesis. [ABSTRACT FROM AUTHOR]

This work describes a novel iron‐catalysed approach for the synthesis of aryl‐substituted benzimidazoles and benzoxazoles. The methodology employs reductive carbonylation using readily available aryl iodides and aryl amines as precursors, with carbon monoxide serving as the efficient carbonyl source. The reaction proceeds under mild conditions with the addition of hydrosilanes and bases. Notably, aryl aldehydes are generated in situ from the aryl iodides, which subsequently react with o‐phenylenediamine or 2‐aminophenol to afford the desired products in high yields. The structures of the synthesized benzimidazoles and benzoxazoles were confirmed using 1H and 13C NMR spectroscopy and mass spectrometry. [ABSTRACT FROM AUTHOR]

An efficient heterogeneous catalytic system for the oxidative aminocarbonylation of alkynes and amines in the presence of CO/O2 to afford substituted propiolamides has been developed. The active nanocatalyst, [Pd/Mg3Al‐LDH]‐300(D), is composed by Pd nanoaggregates (2–3 nm average particle size) stabilized over a partially dehydrated [Mg3Al‐LDH] matrix. The methodology has resulted widely applicable, being the first catalytic system, either homogeneous or heterogeneous, able to activate not only aliphatic amines but also poorly‐nucleophilic aromatic amines. In fact, >60 substituted propiolamides have been synthesized in good to excellent isolated yields through this methodology, being 27 novel compounds. An important characterization effort (XRD, 27Al MAS NMR, TGA, TPD‐CO2, BET area, XPS, HAADF‐HRSTEM and HRTEM) and optimization of the synthesis conditions of the optimal catalyst has been performed. This study, together with a series of kinetic and mechanistic essays, indicates that the optimal catalyst is composed by Pd(0) species stabilized in a partially dehydrated/dehydroxylated LDH material with a Mg/Al molar ratio of 3 and a small crystallite size. All the experimental data indicates that the in situ formation of [PdI2] active species in the material surface together with the presence of a matrix with the optimal acid/base properties are key aspects of this process. [ABSTRACT FROM AUTHOR]

BACKGROUND: Faced with the need to develop new herbicides with modes of action different to those observed for existing agrochemicals, one of the most promising strategies employed by synthetic chemists involves the structural modification of molecules found in natural products. Molecules containing amides, imides, and epoxides as functional groups are prevalent in nature and find extensive application in synthesizing more intricate compounds due to their biological properties. In this context, this paper delineates the synthesis of N‐phenylnorbornenesuccinimide derivatives, conducts biological assays, and carries out in silico investigation of the protein target associated with the most potent compound in plant organisms. The phytotoxic effects of the synthesized compounds (2–29) were evaluated on Allium cepa, Bidens pilosa, Cucumis sativus, Sorghum bicolor, and Solanum lycopersicum. RESULTS: Reaction of endo‐bicyclo[2.2.1]hept‐5‐ene‐3a,7a‐dicarboxylic anhydride (1) with aromatic amines led to the N‐phenylnorbornenesuccinic acids (2–11) with yields ranging from 75% to 90%. Cyclization of compounds (2–11) in the presence of acetic anhydride and sodium acetate afforded N‐phenylnorbornenesuccinimides (12–20) with yields varying from 65% to 89%. Those imides were then subjected to epoxidation reaction to afford N‐phenylepoxynorbornanesuccimides (21–29) with yields from 60% to 90%. All compounds inhibited the growth of seedlings of the plants evaluated. Substance 23 was the most active against the plants tested, inhibiting 100% the growth of all species in all concentrations. Cyclophilin was found to be the enzymatic target of compound 23. CONCLUSION: These findings suggest that derivatives of N‐phenylnorbornenesuccinimide are promising compounds in the quest for more selective and stable agrochemicals. This perspective reinforces the significance of these derivatives as potential innovative herbicides and emphasizes the importance of further exploring their biological activity on weeds. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The covalent organic frameworks/polymers configurated with metal‐N4 conjugated structures offer an exceptional platform for efficient electrochemical CO2 reduction reaction (eCO2RR). However, understanding the impact of the structure‐mediated local microenvironment and integrating CO2 electroreduction with follow‐up utilization toward extending chemical valorization of CO2 are still far from sufficient. Herein, a set of covalent phenanthroline‐porphyrin polymers are designed to decode the microenvironment modulation originating from built‐in structures, and the optimized one delivered an extraordinary performance for eCO2RR with ≈100% Faradaic efficiency of CO under stabilized CO2‐electrolysis of 70 h. The experimental and theoretical analyses suggest that the regulation of the Co‐N4 electronic structures and microenvironment convoys the stabilized formation of key reaction intermediate *COOH. Furthermore, through CO‐mediated electro/thermocatalytic tandem processes, the aminocarbonylation of aryl iodides and amines with high yields has been convincingly implemented over the coordinated Pd sites, which is remarkably helpful to propel extending chemical valorization of CO2. [ABSTRACT FROM AUTHOR]

The covalent organic frameworks/polymers configurated with metal‐N4 conjugated structures offer an exceptional platform for efficient electrochemical CO2 reduction reaction (eCO2RR). However, understanding the impact of the structure‐mediated local microenvironment and integrating CO2 electroreduction with follow‐up utilization toward extending chemical valorization of CO2 are still far from sufficient. Herein, a set of covalent phenanthroline‐porphyrin polymers are designed to decode the microenvironment modulation originating from built‐in structures, and the optimized one delivered an extraordinary performance for eCO2RR with ≈100% Faradaic efficiency of CO under stabilized CO2‐electrolysis of 70 h. The experimental and theoretical analyses suggest that the regulation of the Co‐N4 electronic structures and microenvironment convoys the stabilized formation of key reaction intermediate *COOH. Furthermore, through CO‐mediated electro/thermocatalytic tandem processes, the aminocarbonylation of aryl iodides and amines with high yields has been convincingly implemented over the coordinated Pd sites, which is remarkably helpful to propel extending chemical valorization of CO2. [ABSTRACT FROM AUTHOR]

Reductive N‐11C‐methylation using [11C]formaldehyde and amines has been used to prepare N‐11C‐methylated compounds. However, the yields of the N‐11C‐methylated compounds are often insufficient. In this study, we developed an efficient method for base‐free reductive N‐11C‐methylation that is applicable to a wide variety of substrates, including arylamines bearing electron‐withdrawing and electron‐donating substituents. A 2‐picoline borane complex, which is a stable and mild reductant, was used. Dimethyl sulfoxide was used as the primary reaction solvent, and glacial acetic acid or aqueous acetic acid was used as a cosolvent. While reductive N‐11C‐methylation efficiently proceeded under anhydrous conditions in most cases, the addition of water to the reductive N‐11C‐methylation generally increased the yield of the N‐11C‐methylated compounds. Substrates with hydroxy, carboxyl, nitrile, nitro, ester, amide, and phenone moieties and amine salts were applicable to the reaction. This proposed method for reductive N‐11C‐methylation should be applicable to a wide variety of substrates, including thermo‐labile and base‐sensitive compounds because the reaction was performed under relatively mild conditions (70°C) without the need for a base. [ABSTRACT FROM AUTHOR]

Oxygen vacancies are one of the prominent types of defects in metal oxides. In addition to their role in modifying the electronic properties in solids, these sites have been shown to activate chemical bonds. As a result, the use of defect‐rich metal oxides in the organic transformations is promising. The article gives an overview of various chemical processes that are in use for the chemical reduction of aromatic nitro compounds to amines. Recently, application of oxygen vacancies in transition metal oxide for the selective reduction of aromatic nitro compounds to the corresponding amines has emerged as a new method of synthesis of amines. Oxygen vacancies in reducible oxide such as CuO have been shown to decompose hydrazine hydrate to H2 and in situ cause the reduction of nitro arenes to corresponding amines. This concept article discusses the literature pertaining to the synthesis of nitro reduction reaction, various strategies employed thus far and the place the defect‐mediated synthesis holds. The article also discusses the perspectives and challenges that remain to be addressed to gain more insights into the mechanistic understanding of the role of oxygen vacancies in nitro reduction and beyond. [ABSTRACT FROM AUTHOR]

The purpose of the present research was to study the impact of bitter melon extract (BME) on the generation of heterocyclic aromatic amines (HAAs) in chicken thigh meat. Raw chicken samples were marinated overnight with various levels (0%, 0.5%, and 1%) of BME, and pan‐fried at 150, 200, and 250°C for a total of 10 min. IQx, IQ, MeIQx, MeIQ, 7,8‐DiMeIQx, 4,8‐DiMeIQx, PhIP, AαC, and MeAαC were detected in quantities that varied according to the cooking temperature and the concentration of BME. Notably, IQx, MeIQx, MeIQ, 7,8‐DiMeIQx, 4,8‐DiMeIQx, and AαC levels were reduced through the application of the marinade. Cooking at higher temperatures led to elevated levels of total HAAs. Total HAA levels were 0.98 ± 1.12 ng/g, 3.82 ± 2.12 ng/g, and 6.25 ± 3.35 ng/g in samples cooked at 150, 200, and 250°C, respectively (p <.01). BME demonstrated its effectiveness in mitigating total HAA levels, showing reductions ranging from 25.9% to 69.9%. The most effective concentration of BME in reducing total HAAs was 1% for all cooking temperatures, which might be attributed to its antioxidant activity. These results carry substantial implications for potentially incorporating natural extracts such as BME into chicken products as a viable strategy to reduce HAAs, thus enhancing the safety and quality of meat products. [ABSTRACT FROM AUTHOR]

Cyclopropylmethyl sulfides react with N‐fluorosulfonimide (NFSI) or molecular iodine, enabling C−S cleavage to generate cyclopropylcarbinyl cations, which evolve through cyclopropane ring‐opening reactions into homoallyl cations suitable to react with nucleophiles present in the reaction media. This desulfurative cleavage of cyclopropylmethyl thioethers under non‐acidic conditions facilitates homoallylation of N‐based nucleophiles such as alkyl or aryl amines as well as sulfonimides through a one‐pot protocol in one or two steps depending on the nucleophile. The reaction is initiated by a halogen‐sulfur bond that causes C−S bond cleavage. Moreover, the reaction with iodine proceeds through homoallyl iodide intermediates. [ABSTRACT FROM AUTHOR]

A novel CVO/TiO2 heterojunction material has been prepared and used to catalyze the oxidative aromatization of amines and cyclohexenones under visible light irradiation, avoiding the use of noble metal catalysts and providing an environmentally friendly alternative for the synthesis of aromatic amines. The catalytic reaction uses oxygen as the final oxidant and provides good yields over a wide range of substrates. Notably, the recyclable heterogeneous semiconductor photocatalyst can be readily recovered and reused for at least four cycles. In addition, several biologically active molecules were successfully synthesized using the photocatalytic method. [ABSTRACT FROM AUTHOR]

A catalyst‐free approach has been introduced for the conjugate addition of aromatic amine nucleophiles to α, β‐unsaturated N‐methyl maleimide under microwave irradiation by utilizing water as a promoter. Catalyst‐free, environmentally friendly, short‐reaction time, green solvent, and mild reaction conditions are the advantages of this protocol. This reaction provided good to excellent yields with aromatic anilines as nucleophiles. The benefits of this reaction align with the principles of green and sustainable synthetic chemistry, making it widely applicable in organic synthesis and pharmaceutical chemistry. [ABSTRACT FROM AUTHOR]

A convenient Cu(I) Catalyzed three‐component coupling strategy for the synthesis of polysubstituted pyrroles is developed using simple and readily available building blocks like, 1, 3‐dicarbonyl compound, aryl amine, and β‐nitrostyrene. CuI has been rarely explored for the pyrrole ring synthesis and a comparative analysis of our current catalyst with a range of previously reported catalysts suggested that, CuI is one of the best catalysts for the multicomponent synthesis of polysubstituted pyrrole derivatives. Notably, this process has several advantages, including a simple and practical set‐up with hassle free reaction conditions, extensive substrate scope, short reaction time, high atom economy and environmentally favorable approach. This methodology provides an alternative approach to the highly substituted pyrroles and under optimized reaction conditions, polysubstituted pyrroles were formed in good to excellent yields. Cu(I) catalyzed Mannich reactions followed by Michael addition reactions along with subsequent intramolecular cyclization are believed to be the key steps of this reaction process. [ABSTRACT FROM AUTHOR]

The formation of amide bonds via aminolysis of esters by lipases generates a diverse range of amide frameworks in biosynthetic chemistry. Few lipases have satisfactory activity towards bulky aromatic amines despite numerous attempts to improve the efficiency of this transformation. Here, we report the discovery of a new intracellular lipase (Ndbn) with a broad substrate scope. Ndbn turns over a range of esters and aromatic amines in the presence of water (2 %; v/v), producing a high yield of multiple valuable amides. Remarkably, a higher conversion rate was observed for the synthesis of amides from substrates with aromatic amine rather than aliphatic amines. Molecular dynamics (MD) and quantum mechanical/molecular mechanical (QM/MM) studies showcase the mechanism for the preference for aromatic amines, including a more suitable orientation, shorter catalytic distances in the active site pocket and a lower reaction barrier for aromatic than for aliphatic amines. This unique lipase is thus a promising biocatalyst for the efficient synthesis of aromatic amides. [ABSTRACT FROM AUTHOR]

Synthesis of heteroaryl ortho‐substituted anilines is hitherto challenging. Herein we report scope and limitation of method for annulation of 1‐(2‐nitroaryl)pyrroles and derivatives of 2‐aminobenzyl alcohol to afford ortho‐substituted pyrrolo[1,2‐a]quinoxalin‐4‐yl anilines. Reaction conditions contained elemental sulfur as promoter, while were tolerant of a wide range of aryl and heteroaryl amines. Our method would offer a feasible tactic to yield anilines steric bulk with ortho heterocyclic substituents. [ABSTRACT FROM AUTHOR]

Experimental and theoretical study of the regioselectivity and mechanism of polycyclic aromatic amine (PAA) electrochemical oxidation is important for designing nitrogen doped large π‐conjugated functional molecules. Herein, we used binary‐, ternary‐, and quaternary‐fused PAAs as electro‐oxidative reaction substrates to investigate the yield changes of carbazole and phenazine based aza‐helicene other than oligomers, which were obtained through pyrrole and pyrazine annulation pathways. Combined with the restrained electrostatic potential (RESP) and steric hindrance factor analysis of the substrate, the electron spin density distribution of free radical resonance hybrid and the spin population analysis of the atoms in the structure of each free radical tautomer indicate that the degree of delocalized dispersion of N free radical and the resulting change in the spin density distribution of C free radical tautomers determine the reaction regioselectivity. The potential charge of the K‐region, Bay‐region, and L‐region adjacent to the C(α)−C(β1) bond is higher than that of other regions within the molecule, and the charge in these high RESP regions tends to delocalize more strongly toward electron‐deficient N free radicals. Thus, the activity of N−C(α)−C(β1) region is increased, which supports the proposed free radical addition and free radical coupling mechanism for the electro‐oxidative reaction of PAA. [ABSTRACT FROM AUTHOR]

In this study, chitosan (CS)‐based macromolecular synergistic antioxidant CS‐UC‐TDAA containing carbon–carbon double bond, hindered phenol, and aromatic secondary amine was prepared by using CS,10‐undecenoyl chloride (UC), p‐aminobenzoic acid (AA), 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde (TD) via esterification, Schiff base reaction, and acylation reaction. The molecular structure of CS‐UC‐TDAA was characterized by fourier transform infrared, 1H NMR, and elemental analysis. The effects of macromolecular synergistic antioxidant CS‐UC‐TDAA, small molecular antioxidant TDAA, commercial antioxidant 4020, and butylated hydroxytoluene (BHT) on the antiaging properties of styrene‐butadiene rubber (SBR)/SiO2 composites were systematically studied by accelerated thermo‐oxidative aging test, thermogravimetric (TG) analysis, and methanol Soxhlet extraction experiment. The experimental results show that CS‐UC‐TDAA has more outstanding thermo‐oxidative aging resistance, thermal stability, and solvent extraction resistance in SBR/SiO2 composites than TDAA, 4020, and BHT. The macromolecular synergistic antioxidant CS‐UC‐TDAA endows SBR/SiO2 composites with more durable antiaging performance, which is attributed to the synergistic antioxidant effect of its hindered phenol and aromatic secondary amine groups. Additionally, its resistance to migration and extraction is facilitated by the crosslinking of the carbon–carbon double bond with the rubber and its substantial molecular weight. [ABSTRACT FROM AUTHOR]

The research focused on the photolysis of ortho‐ and para‐substituted aryl azides and the preparation of 2‐arylamino‐substituted azepines. The best results were achieved in 1,4‐dioxane for ortho‐substituted azides and in ethanol for para‐substituted azides, respectively. It was found that reactions with arylamines, which have electron‐donating groups, typically produce higher yields of heterocycles than those with electron‐withdrawing groups. [ABSTRACT FROM AUTHOR]

The demand for natural dyes is increasing due to the negative environmental impacts of synthetic color. In fact, customers are becoming more concerned about their health and the environmentally friendly products. The aim of this research is to disclose the dye extraction process using the ultrasonic method and eco‐friendly dyeing of organic cotton knitted fabric. Initially, 10 g of Syzyguim cumini leaf powder was dissolved in 150 mL of purified water maintaining a 1 : 15 M : L ratio to extract the color. After that, the extracted dye solution was added to coloration bath following the M : L ratios of 1 : 16, 1 : 12, and 1 : 8 for producing dark, medium, and light shades, respectively. Post mordanting was done using natural lemon juice for colorfastness improvement. The color attributes were revealed by the spectrophotometric analysis. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to comprehend the successful relationship that exists among SCL dyes and organic cotton fibers, and the TGA analysis confirmed that dyed fabric is more stable than undyed fabric. Moreover, the colored sample's pH, formaldehyde level, and presence of forbidden Azo groups (aromatic amines) were examined. The test results revealed that very good to excellent color fastness properties were obtained and no harmful chemicals were detected in the dyed samples. [ABSTRACT FROM AUTHOR]

This study describes the palladium‐catalyzed chemoselective amination of chloro(hetero)aryl triflates in the C−Cl bond for the first time. A newly designed and synthesized alkyl‐pyrazole‐based phosphine ligand, L26 (BirdPhos), which is featured with the pyrazole ligand core and the cyclohexyl group at the C3 and C5 positions, was key to the success of this reaction. A variety of chloro(hetero)aryl triflates coupled with aromatic, aliphatic, and heterocyclic amines smoothly afforded the corresponding products up to 97% yields with general chemoselectivity (>99%) in the C−Cl bond. Drug analogs were also synthesized via the chemoselective intermolecular amination. This study attempts to investigate the structure‐activity relationship of this new class of ligand through experimental and density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Reducing nitro compounds to amines is a fundamental reaction in producing valuable chemicals in industry. Herein, the synthesis and characterization of a zirconium metal‐organic framework‐supported salicylaldimine‐cobalt(II) chloride (salim‐UiO‐CoCl) and its application in catalytic reduction of nitro compounds are reported. Salim‐UiO‐Co displayed excellent catalytic activity in chemoselective reduction of aromatic and aliphatic nitro compounds to the corresponding amines in the presence of phenylsilane as a reducing agent under mild reaction conditions. Salim‐UiO‐Co catalyzed nitro reduction had a broad substrate scope with excellent tolerance to diverse functional groups, including easily reducible ones such as aldehyde, keto, nitrile, and alkene. Salim‐UiO‐Co MOF catalyst could be recycled and reused at least 14 times without noticeable losing activity and selectivity. Density functional theory (DFT) studies along with spectroscopic analysis were employed to get into a comprehensive investigation of the reaction mechanism. This work underscores the significance of MOF‐supported single‐site base‐metal catalysts for the sustainable and cost‐effective synthesis of chemical feedstocks and fine chemicals. [ABSTRACT FROM AUTHOR]

A facile intramolecular [1,5] hydride transfer reaction in a Dihydroquinazolin‐4(1H)‐one moiety synthesized from anthranilamide, glutaraldehyde, and aromatic amines is described in isopropanol medium in the presence of catalytic HCl. Based on that, we have designed a simple, efficient strategy for conjugating quinazolinone, a pharmaceutically active moiety, with an aromatic amine through an aliphatic spacer. The use of isopropanol as a reaction medium at RT and isolation of the product without rigorous column purification make the process a step ahead towards sustainability. One of the synthesized compounds was evaluated as a small molecule DNA binder. Detailed binding properties were investigated by the multispectroscopy methods. [ABSTRACT FROM AUTHOR]

In this report, we describe the use of amino‐λ3‐iodanes in the electrophilic amination of arylboronic acids and boronates. Iodine(III) reagents with transferable amino groups, including one with an NH2 group, were synthesized and used in the amination, allowing the synthesis of a wide range of primary and secondary (hetero)arylamines. Mechanistic studies by DFT calculations indicate that the reaction proceeds through an electrophilic amination process from a tetravalent borate complex with a B−N dative bond. [ABSTRACT FROM AUTHOR]

A total synthesis strategy was developed for the synthesis of luotonin A, B and their analogues using synergistic FeCl3/KI‐catalyzed oxidative cyclization. This protocol utilizes cheap and widely available N‐propargyl 2‐methyl‐quinazolinones and arylamines under mild conditions, and it has a wide substrate scope and high atom economy. Different natural products (luotonin A, B and derivatives) can be synthesized via a unique switchable approach. Further transformations from luotonin B to luotonin E and structural modification of natural products demonstrate the potential applications of this method. Moreover, camptothecin can also be modified with the reported protocol to afford the hydroxyl‐substituted product. [ABSTRACT FROM AUTHOR]

Benzoxazole‐linked covalent organic frameworks (BO−COFs), despite their exceptional chemical stability, are still in their infancy. This is primarily because the current prevalent methods require the use of special ortho‐hydroxyl‐substituted aromatic amines as monomers. Herein, we report an innovative strategy to access BO−COFs directly from imine‐linked COFs (Im−COFs) without pre‐embedded OH groups, using a two‐step sequential oxidation/cyclization process. The two‐step process included the oxidation of Im−COFs into amide‐linked COFs, followed by a copper‐catalyzed oxidative cyclization. Five representative BO−COFs were synthesized with retained crystallinity and high oxidization efficiency, offering the potential to convert a significant portion of Im−COFs into BO−COFs. The structural advantages of the newly designed BO−COFs were demonstrated through their application to photocatalytic organic transformations. [ABSTRACT FROM AUTHOR]

Herein, the use of triphenylmethylium tetrakis(pentafluorophenyl)borate as an efficient catalyst for the intermolecular dehydrative coupling of p‐hydroxymandelic acid hydrate with substituted aromatic amines and (thio)phenols was developed, which allows for the preparation of arylacetic acid derivatives in a convenient manner. Notably, this method offers several advantages, including being prefunctionalization free, high atom efficiency, and high regioselectivity. Additionally, it exhibits a broad substrate scope, enabling the synthesis of a range of arylacetic acid derivatives. Furthermore, this method can also be applied to the etherification of arylthiol derivatives, facilitating the preparation of various thiolated products, which would enhance the applicability and potential utility of this method in organic synthesis. [ABSTRACT FROM AUTHOR]

The 1,2‐rearrangement reaction is one of the most important approaches to construct carbon‐carbon bonds in organic synthesis. However, the development of catalytic asymmetric 1,2‐rearrangements is still far from mature and often suffers from problems such as complex substrates, single product structure, and lack of synthetic application. Multicomponent reaction has been recognized as a robust tool for the synthesis of diverse and tunable products from readily available starting material. Conceptionally and practically, the development of multicomponent asymmetric 1,2‐rearrangements is highly desirable. In this regard, we report herein a three‐component benzilic acid‐type rearrangement of 2,3‐diketoesters, aromatic amines and aldehydes for the asymmetric construction of synthetically challenging pyrrolinones bearing aza‐quaternary stereocenters. To the best of our knowledge, this reaction represents the first example of organocatalyzed multicomponent asymmetric 1,2‐rearrangements. [ABSTRACT FROM AUTHOR]

Although closed‐loop recycling of dynamic covalent bond‐based plastics does not require catalysts, their mechanical strength and chemical stability remain a major concern. In this study, closed‐loop recyclable poly(aryl imine) (PAI) plastics with high mechanical strength and excellent chemical resistance are fabricated by copolymerizing aromatic amines and aromatic aldehydes through dynamic imine bonds. The resulting PAI plastic with a tensile strength of 58.2 MPa exhibits excellent chemical resistance and mechanical stability in acidic and basic aqueous solutions and various organic solvents. The PAI plastics can be depolymerized in a mixed solvent of tetrahydrofuran (THF)/HCl aqueous solution through the dissociation of imine bonds, and the monomers can be facilely recovered with high purity and isolated yields due to the solubility difference between the aromatic amines and aromatic aldehydes in selective solvents. The efficient closed‐loop recycling of the PAI plastic can also be realized through monomer conversion because the hydrolysis of the aromatic aldehydes generates aromatic amines. The recovered monomers can be used to re‐fabricate original PAI plastics. This PAI plastic can be selectively recovered from complicated mixed polymer waste streams due to the mild depolymerization conditions of the PAI plastic and its high stability in most organic solvents. [ABSTRACT FROM AUTHOR]

Herein, we disclose a facile and efficient electrochemical method for the dibromination of aryl amines by double functionalization of aromatic C(sp2)−H (both para and ortho) under metal‐ and external oxidant‐free conditions at room temperature for the first time. The reaction is demonstrated using 1,2‐dibromoethane to dibrominate a wide range of N‐substituted aryl amines in a simple setup with C(+)/Pt(−) electrodes under mild reaction conditions. This transformation proceeds smoothly with a broad substrate scope affording the valuable and versatile N‐substituted 2,4‐dibromoanilines in moderate to excellent yields with high regioselectivity. In this paired electrolysis, cathodic reduction of 1,2‐DBE followed by anodic oxidation generates bromonium intermediates, which then couple with anilines to furnish the dibrominated products. It represents a distinctive approach to challenging redox‐neutral reactions. The versatility of the electrochemical ortho‐, para‐dibromination was reflected by unique regioselectivities for challenging aryl amines and gram‐scale electrosynthesis without the use of a stoichiometric oxidant or an activating agent. [ABSTRACT FROM AUTHOR]

Cheap, stable and easy‐to‐handle Werner ammine salts have been known for more than a century; but they have been rarely used in organic synthesis. Herein, we report that the Werner hexammine complex [Ni(NH3)6]Cl2 can be used as both a nitrogen and a catalytic nickel source that allow for the efficient amination of aryl chlorides in the presence of a catalytic amount of bipyridine ligand under the irradiation of 390–395 nm light without the need of any additional catalysts. More than 80 aryl chlorides, including more than 20 drug molecules, were aminated, demonstrating the practicality and generality of this method in synthetic chemistry. A slow NH3 release mechanism is in operation, obviating the problem of catalyst poisoning. Still interestingly, we show that the Werner salt can be easily recovered and reused, solving the problem of difficult recovery of transition metal nickel catalysts. The protocol thus provides an efficient new strategy for the synthesis of primary aryl amines. [ABSTRACT FROM AUTHOR]

Meta‐aramid fibre exhibits poor dyeing performance when treated using conventional dyeing methods. In this study, coloration of meta‐aramid fabrics was performed at room temperature utilising diazonium salts from weakly basic aromatic amines and was achieved via in situ construction of azo chromophores on the meta‐phenylenediamine moiety. To promote diazonium‐salt penetration into the meta‐aramid fibre, the pretreatment of meta‐aramid fabrics with dimethyl sulfoxide at 55°C for 30 min and the utilisation of methanol were involved during the coloration process. As a result, the fabrics could be coloured with deep, levelled and firm shades of brown series. The azo chromophore is derived from the skeleton of the polyamide chain. Therefore, the coloured fabrics exhibit good resistance to organic solvents as well as good to excellent colour fastness to soaping, rubbing and sublimation. A study of the coloration mechanism revealed that the terminal and middle meta‐phenylenediamine moieties serve as the main coupling reaction sites. When treated with a diazonium salt, the highly reactive terminal meta‐phenylenediamine moiety reacted first and generated chromophores with an absorption peak in the long‐wavelength region. However, such chromophores only contributed a limited colour depth owing to the limited number of the terminals. If excess diazonium salts were used, the main hue can be attributed to the azo chromophores based on the massive middle meta‐phenylenediamine moieties, although these moieties are less reactive than the terminal meta‐phenylenediamine moieties. [ABSTRACT FROM AUTHOR]

Axially chiral diaryl ethers are present in numerous natural products and bioactive molecules. However, only few catalytic enantioselective approaches have been established to access diaryl ether atropisomers. Herein, we report the N‐heterocyclic carbene‐catalyzed enantioselective synthesis of axially chiral diaryl ethers via desymmetrization of prochiral 2‐aryloxyisophthalaldehydes with aliphatic alcohols, phenol derivatives, and heteroaromatic amines. This reaction features mild reaction conditions, good functional group tolerance, broad substrate scope and excellent enantioselectivity. The utility of this methodology is illustrated by late‐stage functionalization, gram‐scale synthesis, and diverse enantioretentive transformations. Control experiments and DFT calculations support the association of NHC‐catalyzed desymmetrization with following kinetic resolution to enhance the enantioselectivity. [ABSTRACT FROM AUTHOR]

In this article, a crosslinked waterborne poly(urethane‐urea) (WPUU) is synthesized based on the terminal aromatic amine polyether (DP‐1000) and aliphatic isophorone diisocyanate. Then WPUU is compound with acrylate monomer by emulsion polymerization to produce waterborne polyacrylate–poly(urethane‐urea) (WPUUA) hybrid emulsions. Compared with waterborne polyacrylate (WPA) film, the film‐forming ability of WPUUA film is improved and the surface roughness Ra and Rq of WPUUA film decreases from 47.5 and 36.4 nm to 35.2 and 18.8 nm, respectively. Meanwhile, the mechanical properties of WPUUA films are significantly improved compared to WPA film. In addition, the performances of WPUUA hybrid films can be modified according to requirements by adjusting the molar ratio between DP‐1000 and polyisocyanate. As a result, these WPUUA hybrid emulsions have great application potential in waterborne coatings and other fields. [ABSTRACT FROM AUTHOR]

Methylenedianiline (MDA) is a secondary, undesired, product of the glycolysis process of polyurethane (PU) scraps due to hydrolysis and pyrolysis side reactions. As an aromatic and carcinogen amine, MDA poses different problems in handling, transporting, and labelling recycled polyols derived from glycolysis, hindering the closure of PU recycling loop. Aiming to provide a solution to this issue, in this work different deaminating agents (DAs) were investigated with the purpose of analyzing their reactivity with MDA. A first part of the study was devoted to the analysis of MDA formation as a function of reaction time and catalyst concentration (potassium acetate) during glycolysis. It was observed that the amount of MDA increases almost linearly with the extent of PU depolymerization and catalyst content. Among the DAs analyzed 2‐ethylhexyl glycidyl ether (2‐EHGE), and acetic anhydride (Ac2O) showed interesting performance, which allowed MDA content to be diminished below the limit for labelling prescription in 30 minutes. PU rigid foams were, therefore, synthesized from the corresponding recycled products and characterized in terms of thermal and mechanical performance. Ac2O‐deaminated polyols led to structurally unstable foams with poor compressive strength, while 2‐EHGE‐deaminated products allowed the production of foams with improved mechanical performance and unaltered thermal conductivity. [ABSTRACT FROM AUTHOR]

Herein, we report that bulky alkylphosphines such as PtBu3 can switch the roles from actor to spectator ligands to promote the FeCl2‐catalyzed N‐amidation reaction of arylamines with dioxazolones, giving hydrazides in high efficiency and chemoselectivity. Mechanistic studies indicated that the phosphine ligands could facilitate the decarboxylation of dioxazolones on the Fe center, and the hydrogen bonding interactions between the arylamines and the ligands on Fe nitrenoid intermediates might play a role in modulating the delicate interplay between the phosphine ligand, arylamine, and acyl nitrene N, favoring N−N coupling over N−P coupling. The new ligand‐promoted N‐amidation protocols offer a convenient way to access various challenging triazane compounds via double or sequential N‐amidation of primary arylamines. [ABSTRACT FROM AUTHOR]

The construction of C−N bonds is considered one of the most useful reactions in synthetic chemistry due to their widespread presence in pharmaceuticals, natural products, etc. Pd‐catalyzed Buchwald–Hartwig amination (BHA) has provided the most efficient method to form (hetero)aryl amines but it required strong base and sophisticated ligands. In comparison, the combination of photocatalysis and nickel chemistry has revolutionized catalytic strategies and is emerging as a quintessence to realize BHA, termed as Ni‐metallaphotoredox BHA. To pursue a universal protocol, diverse photocatalysts were designed and employed in Ni‐metallaphotoredox BHA, and smoothly promoted C−N bond formations under irradiation of light from ultraviolet to red light, respectively. Note that the matching of photocatalyst and light was critical for success. Therefore, this review mainly focuses on the discussion of Ni‐metallaphotoredox BHA according to the irradiation light's wavelength, covering ultraviolet, purple, blue, red, and white light as well as solar light. We try to find a clue in the relationship of structure‐photophysical behaviors of photocatalysts under the same or different irradiation light. At last, current limitations and potential trends for advancing Ni‐metallaphotoredox BHA are highlighted. We deem that it could encourage chemists to continue designing suitable photocatalyst for C−N bond formations under sunlight mimicking plants' photosynthesis. [ABSTRACT FROM AUTHOR]

Photoelectrochemistry is becoming an innovative approach to organic synthesis. Generally, the current photoelectrocatalytic organic transformations suffer from limited reaction type, low conversion efficiency and poor stability. Herein, we develop efficient and stable photoelectrode materials using metal oxide protective layer, with a focus on achieving regioselective activation of amine compounds. Notably, our photoelectrochemistry process is implemented under mild reaction conditions and does not involve any directing groups, transition metals or oxidants. The results demonstrate that beyond photocatalysis and electrocatalysis, photoelectrocatalysis exhibits high efficiency, remarkable repeatability and good functional group tolerance, highlighting its great potential for applications. [ABSTRACT FROM AUTHOR]

Three‐component tandem Ritter and Mannich reactions were developed for one‐pot arylation and acyl protected amination of isatin. The acid catalyzed reaction produced wide variety of 3‐aryl‐3‐amidooxindoles directly from commercially available isatin. The C3 functionalization of isatin is affected by condensation with electron rich arenes and nitriles or amides with concomitant C−C and C−N bonds formation. Substituted isatins, different nucleophiles (cyclic and acyclic N, N‐disubstituted arylamines), aliphatic nitriles, and amides expanded the scope of the reaction. The reaction is simple, general, efficient and can switch the amidation substrate from nitriles in Ritter reaction to amides in Mannich reaction. [ABSTRACT FROM AUTHOR]

Profile modification is the key for efficient development of oil and gas reservoirs, especially high‐temperature reservoirs, which requires the system to have good high‐temperature resistance. According to the characteristics of high‐temperature reservoir, a high temperature gel composed of terpolymer, modified phenolic resin, aromatic amine curing agent and thiourea was developed. The effects of different components on the properties of the gel system were clarified. Then, the long‐term thermal stability under high‐temperature conditions was studied. In addition, the plugging performance of gel system under different permeability and injection volume was studied. Finally, the gelation properties and plugging properties of gel system with the flow distance were studied by simulating the flow of porous media. The results show that the gel system has high strength and suitable gelation time, and it can be adjusted in real time according to different oilfield requirements. In the range of 75–150°C, the gel system had excellent long‐term stability. When the temperature was 75°C, no free water after 120 days, and the viscosity only decreased from 13,131 to 11,254 mPa·s. Even at 150°C, the viscosity was as high as 8350 mPa·s after 120 days, and the free water was only 5.5%. The gel system had good adhesion ability on the porous media surface and strong anti‐flooding properties. When the injection volume was 0.1 pore volume (PV in short), the plugging rate to the sand packed tube was 72.7%. When the injection volume was 0.5 PV, the plugging rate was as high as 97.6%. The plugging rate of the gel system for the sand packed tube with permeability of 500 mD was 98.7% when the injection volume was 0.5 PV. When the permeability increased to 3000 mD, the plugging rate still reached 92.3%. The gel system also had an excellent deep profile control ability, and the viscosity retention of at 60 cm was as high as 96%. When the flow distance was 2 m, the viscosity retention also reached 75%. The rheological properties also shown that the gel system had excellent shearing resistance and adsorption resistance. Finally, combined with the state of the gel system on the surface of the porous media, there was no cementation between the formation sand before the injection, and the sand particles did not stick to each other. After the gel was injected, the adhesion of gel system on the porous media surface was very strong. The 3D network structure was also very dense, the sand particles could have good cementation effect under the adhesion of gel system. [ABSTRACT FROM AUTHOR]

A visible‐light induced multicomponent reaction of aromatic aldehydes, amines and sodium difluoromethanesulfinate for the synthesis of fluorinated secondary amines has been investigated. The protocol affords a convenient pathway for the introduction of difluoromethyl group into imines, which generated in situ by the reaction of aldehydes and amines. A diverse range of fluorinated secondary amines were synthesized in 43%–79% yields under room temperature. In addition, a plausible mechanism was proposed based on several control experiments. [ABSTRACT FROM AUTHOR]

Axially chiral N-arylindoles bearing a stereogenic C-N axis are unique important scaffolds in natural products, advance materials, pharmaceuticals and privileged chiral ligands or catalysts. Herein, we report the direct synthesis of C-N axially chiral N-arylindoles through a Pd-catalyzed free amine-directed atroposelective C-H olefination enabled by a spiro phosphoric acid (SPA) ligand. A wide range of enantioenriched N-aromatic amine indoles were obtained in high yields with good enantioselectivities (35 examples, up to 91% yield and up to 96% ee). The chiral products with free amine group offer an effective functional handle for down-stream diversity-oriented synthesis. [ABSTRACT FROM AUTHOR]

We have developed a visible‐light‐mediated synthesis of 3‐arylsulfonylated thioflavones using an in situ‐activation strategy. The reaction proceeds through a one‐pot, three‐component pathway, without the need for sensitive or harsh reaction conditions. Organic photocatalysts were employed to generate aryl radicals more efficiently from aryl diazonium salts generated in situ. This method enables the synthesis of 3‐arylsulfonylated thioflavones from aryl amines and methylthiolated alkynones, utilizing potassium metabisulfite as an inexpensive source of sulfur dioxide. The resulting products were obtained under mild reaction conditions. This approach provides an efficient alternative pathway for synthesizing thioflavone derivatives, which are prevalent among various bioactive compounds. [ABSTRACT FROM AUTHOR]