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This article predicts bending very high cycle fatigue (VHCF) life of three typical nickel‐based alloys SM2550, BG2532, and G3 used for completion strings. Fatigue tests were conducted on the three alloys using an ultrasonic fatigue system at a frequency of 20 kHz. The results showed that the fatigue strength ranges of the three alloys were markedly different, reflecting their different sensitivities to fatigue loading. Scanning electron microscope observations revealed numerous fatigue crack origins with internal decohesion in the fatigue source region. To achieve unified prediction of the fatigue life for the three alloys, a prediction model based on deep learning was built with inputs including fatigue initiation quantity, cleavage facet size, and other fatigue fracture characteristics. It was found that single source feature was insufficient to obtain satisfactory prediction accuracy for all alloys, while multifeature coupling integration could significantly improve the prediction precision, enabling reliable prediction of alloy fatigue life. This study provides new insights into bending VHCF life prediction. Highlights: This article predicts bending VHCF life for three completion strings.Bending VHCF life model utilizing deep wise separable convolution was established.Deep learning can effectively integrate with bending VHCF analyses. [ABSTRACT FROM AUTHOR]

Transition–metal catalyzed tandem asymmetric reactions were powerful tools to access various chiral compounds. Many strategies have been developed for the coupling of 1,n‐dienes with aryl halides via a tandem Heck/Tsuji–Trost process. However, the control of regio‐ and stereo‐chemistry remains a challenging task. This minireview details the recent advances in the field of asymmetric Heck/Tsuji–Trost reactions catalyzed by palladium complex, which have opened new opportunities and expanded our understanding in this area of research in recent years. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Herein, we report nickel‐catalyzed cross‐coupling of gem‐difluorinated cyclopropanes with boronic acids, providing the corresponding arylated 2‐fluoroallylic scaffolds. This approach used commercially available phosphine ligand Xantphos to obtain monofluorinated alkenes with high regioselectivity and Z‐stereoselectivity. Mechanistic studies proposed a Ni(II)‐fluoroallyl pathway and excluded the radical pathway. Meanwhile, DFT study of the reductive elimination clarified the origin of the high linear selectivity. [ABSTRACT FROM AUTHOR]

Silicone rubbers are widely employed in various fields such as electronics, electrical engineering, mobile communications, aerospace, and automotive industries. However, silicone rubbers are typically challenging to reprocess and degrade. Moreover, with the advancement of technology, higher demands are placed on its thermal conductivity and dielectric properties. In this study, diglycidyl ether terminated polydimethylsiloxane is cured by 4,4′‐dithiodibutyric acid which contains dual dynamic covalent disulfide and ester bonds with triazobicyclodecene as the ester exchange catalyst to prepare silicone rubber vitrimers (SRVs) through a casting method. The SRVs demonstrate a relatively higher intrinsic thermal conductivity of 0.26 W (m⁻1 K⁻1) compared to ≈0.20 W (m⁻1 K⁻1) of conventional silicone rubber. Besides, the SRVs exhibit very low and stable dielectric constant and dielectric loss at both low and high frequencies (X‐band). The lowest dielectric constant and dielectric loss tangent at 10 GHz are 2.75 and 0.0650, respectively. Besides, the dual dynamic covalent bonds enable the SRVs to have excellent reprocessability and fast degradability. Moreover, the SRVs reveal UV‐shielding capability, as the transmittance of the SRVs is 0% from 200 to 400 nm of UV light. [ABSTRACT FROM AUTHOR]

The palladium‐catalyzed asymmetric carboamination reaction is one of the most significant transformations in organic chemistry. Herein, we report the first palladium‐catalyzed asymmetric alleneamination of β,γ‐unsaturated hydrazones with propargylic acetates. This protocol enables the efficient installation of various multisubstituted allene groups onto dihydropyrazoles in good yields with excellent enantioselectivities. The chiral sulfinamide phosphine ligand Xu‐5 exhibits highly efficient stereoselective control in this protocol. The salient features of this reaction include the readily available starting materials, a broad substrate scope, an easy scale‐up, mild reaction conditions and versatile transformations. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Branched fluorine/adamantane PBO precursor (preFABPBO), synthesized via random co‐condensation between 2,2‐bis(3‐amino‐ 4‐hydroxyphenyl)hexafluoro propane, 1,3‐adamantanedicarbonyl dichloride, and trimesoyl chloride, is performed as interfacial compatibilizer, bisphenol A dicyanate ester (BADCy) resin as polymer matrix, and poly(p‐phenylene‐2,6‐benzobisoxazole) (PBO) fibers as reinforcements to prepare PBO fibers/FABPBO‐BADCy wave‐transparent laminated composites by high temperature molding. The mechanical properties, wave‐transparent performances, and heat resistances of PBO fibers/BADCy composites are simultaneously improved by the addition of preFABPBO. The interlaminar shear strength (ILSS) and flexural strength of PBO fibers/FABPBO‐BADCy composites are 48.9 and 665.3 MPa, respectively, increased by 33.2% and 13.3% compared to those of PBO fibers/BADCy composites (36.7 and 587.4 MPa). The dielectric constant and dielectric loss values at 106 Hz are 2.53 and 0.003, respectively, lower than those of PBO fibers/BADCy composites (3.06 and 0.006), and the corresponding wave transmission efficiency is 94.8%, which also presents excellent stability over the wide temperature (25—200 °C) and frequency range (103—107 Hz and 8.2—12.4 GHz). Meanwhile, the heat resistance index and glass transition temperature are 229.9 °C and 247.5 °C, also better than those of PBO fibers/BADCy composites (229.6 °C and 247.1 °C). [ABSTRACT FROM AUTHOR]

Central chirality is an important chiral element used in the design of chiral ligands and catalysts. Mostly, the attention of organic chemists is focused on developing of chiral ligands with stable stereogenic centers. However, the N‐chirality in chiral ligand design has been rarely explored due to its flexibility. Here we demonstrate the design, synthesis, and application of a class of simple P,N‐ligands with flexible N‐chirality and their derived iridium complexes with fixed N‐chiral stereocenters. Both fixed configurations of the N‐stereocenter of the iridium complexes could be selectively formed from the same chiral ligand. This pair of diastereoisomeric iridium complexes showed good performance in the enantiodivergent asymmetric hydrogenation of exocyclic α,β‐unsaturated lactams. The N−H group plays an impressive role in catalytic activity. Computational studies emphasized the importance of N‐chirality and N−H group. [ABSTRACT FROM AUTHOR]

Chiral perhydroindoles are found in a number of natural products and biologically active compounds. Therefore, the development of new asymmetric methodology for rapid access to this core is of high importance. Herein, we reported a highly regio‐ and diastereo‐selective palladium/PC‐Phos‐catalyzed asymmetric Heck/Tsuji–Trost reactions of readily available amino tethered 1,3‐cyclohexadienes with aryl and alkenyl halides, delivering various functionalized chiral hexahydroindoles in good yields with high enantioselectivity. The application of this reaction to the concise synthesis of (−)‐α‐Lycorane was demonstrated. DFT computation results indicate that the difference in ΔEdis of two migration insertion transition states determines the enantioselectivity of the reaction. [ABSTRACT FROM AUTHOR]

BACKGROUND: The diamondback moth (DBM), Plutella xylostella (L.), is the most destructive pest of cruciferous vegetables worldwide. Chlorfenapyr is an important insecticide for controlling DBM. The impacts of three sublethal doses (LC1, LC10 and LC30) of chlorfenapyr on the chlorfenapyr‐exposed DBM individuals and their unexposed F1 and F2 offspring were investigated in order to reveal the non‐lethal deleterious effects of chlorfenapyr and its potential hormetic effects. RESULTS: LC1 significantly increased female pupa weight of F0 and F1 generations, and F0 fecundity as well as F1 gross reproduction rate (GRR). The LC1‐elicited rise in emergency rate and fecundity was significantly greater in F0 than in F1. By contrast, LC30 significantly decreased age‐specific survival rates, pupation rate, male pupal weight, emergence rate and fecundity of F0 and F1 generations as well as female adult proportion and GRR, net reproduction rate (R0), intrinsic rate of increase (rm) and finite rate of increase (λ) of F1 generation. The LC30‐induced reductions in pupation rate, adult emergence rate, male and female pupa weight, and fecundity were greater in F1 than in F0. While LC10 elicited only a mild inhibition (extension of pupal duration) in F0, it yielded both deleterious (drops in female proportion and age‐specific survivals) and hormetic effects (ups in male longevity and female fecundity) in F1. CONCLUSION: The results demonstrate that the sublethal effects of chlorfenapyr on DBM vary from inhibition to stimulatory hormesis, depending on the dose and generation. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

A Pd‐catalyzed synthesis of 1,2,3,4‐tetrahydroisoquinoline (THIQ) via cyclization of ortho‐bromophenethyl tosylamides with aryl N‐tosylhydrazones in the presence of base was developed. The reaction is believed to proceed via the oxidative addition of palladium with ortho‐bromophenethyl tosylamides, followed by carbene insertion and cyclization. The carbene species were generated in‐situ from the aryl N‐tosylhydrazones and KOtBu. [ABSTRACT FROM AUTHOR]

Excess iron accumulation occurs in organs of patients with certain genetic disorders or after repeated transfusions. No physiological mechanism is available to excrete excess iron and iron overload to promote lipid peroxidation to induce ferroptosis, thus iron chelation becomes critical for preventing ion toxicity in these patients. To date, several iron chelators have been approved for iron chelation therapy, such as deferiprone and deferoxamine, but the current iron chelators suffer from significant limitations. In this context, new agents are continuously sought. Here, a library of new deferric amine compounds (DFAs) with adjustable skeleton and flexibility is synthesized by adopting the beneficial properties of conventional chelators. After careful evaluations, compound DFA1 is found to have greater efficacy in binding iron through two molecular oxygens in the phenolic hydroxyl group and the nitrogen atom in the amine with a 2:1 stoichiometry. This compound remarkably ameliorates iron overload in diverse murine models through both oral and intravenous administration, including hemochromatosis, high iron diet‐induced, and iron dextran‐stimulated iron accumulation. Strikingly, this compound is found to suppress iron‐induced ferroptosis by modulating the intracellular signaling that drives lipid peroxidation. This study opens a new approach for the development of iron chelators to treat iron overload. [ABSTRACT FROM AUTHOR]

The key to address the cost issue of polymer electrolyte membrane fuel cells (PEMFCs) lies on reducing Pt amount employed in cathode catalyst layers (CCLs). In past decades, researchers focus on developing series of alloy and core–shell electrocatalysts with high oxygen reduction reaction activity in order to alleviate the low Pt loading caused performance loss. However, it is noted that the concentration polarization loss resulting from the cathode oxygen transport plays a more important role as the Pt loading decreases, especially the local oxygen transport through the ultrathin ionomer film covering on Pt surface. This paper reviews the nanomorphology of the ultrathin perfluorinated sulfonic acid ionomer film in CCLs, as well as the local oxygen transport mechanism and the corresponding effects on fuel cell performance in low Pt PEMFCs. In addition, both the detailed local oxygen transport properties in carbon black‐supported Pt membrane electrode assemblies (MEAs) and high surface carbon‐supported MEAs are summarized. Subsequently, numerous innovative strategies and effective approaches of reducing the local oxygen transport resistance are introduced. The new insights proposed in this paper have important implications for enhancing local oxygen transport and designing high‐performance fuel cell electrodes. [ABSTRACT FROM AUTHOR]

The asymmetric catalytic addition of linear Grignard reagents to ketones has been a long‐standing challenge in organic synthesis. Herein, a novel family of PNP ligands (W‐Phos) was designed and applied in copper‐catalyzed asymmetric addition of linear Grignard reagents to aryl alkyl ketones, allowing facile access to versatile chiral tertiary alcohols in good to high yields with excellent enantioselectivities (up to 94 % yield, 96 % ee). The process can also be used to synthesize chiral allylic tertiary alcohols from more challenging α,β‐unsaturated ketones. Notably, the potential utility of this method is demonstrated in the gram‐scale synthesis and modification of various densely functionalized medicinally relevant molecules. [ABSTRACT FROM AUTHOR]

Proton exchange membrane water electrolysis (PEMWE) is a key technology to solve the serious energy and environmental problems. However, the poor durability of electrocatalysts in acidic oxygen evolution reaction (OER) environment hinders the large‐scale application of PEMWE. Herein, a robust RuMn electrochemical catalyst with a remarkable durability within 20 000 cyclic voltammetry cycles is reported. Furthermore, RuMn is stable for 720 h at 10 mA cm–2 current density in 0.5 M H2SO4 solution with <100 mV overpotential increase, outperforming the most electrocatalysts reported to date, by far. An amorphous RuOx shell is detected after the OER test, indicating a surface reconstruction process on the catalyst that inhibits steady‐state dissolution. Further study demonstrates that the excellent durability of RuMn realized by protective RuOx can be attributed to strong bond strength of Ru, which is supported by density functional theory calculations with high dissolution voltage. Thus, improving the bond strength of Ru extends the design strategy for the Ru‐based alloy catalysts with considerable stability. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A highly enantioselective gold‐catalyzed intermolecular [3 + 2] cycloaddition of N‐allenamides with nitrones was realized by the application of Ming‐Phos M6 as a chiral ligand. Both enantiomers of the cycloadducts with opposite configuration could be obtained in high yields with high regio‐ and enantioselectivity by the employment of either diastereomer of the chiral ligand. The acidic N—H bond (hydrogen bonding) of sulfinamide moiety of Ming‐Phos and pentaflurophenyl substituent (fluorine effect) may play important roles in enhancement of enantioselectivity, that is, Ming‐Phos is a multifunctional ligand in this transformation. [ABSTRACT FROM AUTHOR]

γ‐Butenolide and γ‐butyrolactone scaffolds are two types of important core structures in numerous natural products and bioactive targets. However, methods to construct the chiral quaternary arylated γ‐butenolide are rarely explored. We herein report an efficient Pd‐catalyzed enantioselective γ‐arylation of β,γ‐unsaturated butenolides with aryl bromides, which shows high γ‐selectivity, good functional group tolerance and excellent enantioselectivity. Notably, this protocol also allows for facile construction of tricyclic tetrahydroindolines and tetrahydroisoquinolinones in one step. DFT calculations are consistent with the experimental results, suggesting that the γ‐arylation is favoured over the α‐arylation. Finally, this method is applied to the rapid synthesis of natural product (R)‐(+)‐boivinianin A. [ABSTRACT FROM AUTHOR]

To meet the high‐speed commercialization demands of electrochemical energy storage and conversion devices, the development of high‐performance and low‐cost electrode materials is urgently necessary. Mesoporous carbon, which shows excellent intrinsic characteristics and flexible structure, has raised a surge of interest recently since it offers opportunities for improving the energy or power density and durability as well as reducing the cost of electrodes. In this paper, we first review primary methods for preparing mesoporous carbons. Next, the obstacles in lithium batteries, supercapacitors, proton exchange membrane fuel cells and water electrolyzers are analyzed and the recent progresses of mesoporous carbon based electrode designs in solving these obstacles are systematically introduced. Finally, we outline current challenges and future directions of developing mesoporous carbon based electrode materials in electrochemical energy storage and conversion devices. In creating this review, we hope to give a succinct introduction to the mesoporous carbon and provide meaningful references for its future research. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Atropisomeric anilides are one of important C—N axially chiral compounds. Compared with the N‐terminal functionalization to prepare such compounds, C‐terminal functionalization strategies have been rarely reported. We describe herein an efficient synthesis of axially chiral anilides enabled by Pd‐catalyzed desymmetric Sonogashira cross‐coupling reactions with the use of a newly identified Ming‐Phos. Moderate to high yields with high enantioselectivities (up to 98% ee) were obtained. [ABSTRACT FROM AUTHOR]

Electrochemical nitrogen reduction reaction (NRR) is intensively investigated by researchers for its potential to be the next‐generation technology to produce ammonia. Many attempts have been made to explore the possibility of electrochemical ammonia production catalyzed by noble metals. However, the produced ammonia in most reported cases is in ppm level or even lower, which is susceptible to potential contaminants in experiments, leading to fluctuating or even contradictory results. Herein, a rigorous procedure was adopted to systematically evaluated the performance of commercial noble metal nanocatalysts toward NRR. No discernible amount of ammonia was detected in either acidic or alkaline solutions. Further, nitrogen‐containing contaminants in catalysts that might cause false positive results were detected and characterized. An effective way to remove pre‐existing pollutants by consecutive cyclic voltammetry scan was proposed, helping to obtain reliable and reproducible results. [ABSTRACT FROM AUTHOR]

The integration of intrinsic thermal conductivity and intrinsic flame retardancy of epoxy resins shows wider application prospects in electricals and electronics. Discotic liquid crystal epoxy (D‐LCE) is synthesized from pyrocatechol, 2‐allyloxyethanol, and 3‐chloroperoxybenzoic acid. P/Si synergistic flame‐retardant co‐curing agent (DOPO‐POSS, DP) is synthesized from p‐hydroxybenzaldehyde, 9, 10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide (DOPO), and amino terminated polysilsesquioxane (POSS). Finally, D‐LCE is cured within liquid crystal range with 4, 4′‐diaminodiphenyl methane (DDM) and DP, to obtain intrinsic highly thermal conductive/flame‐retardant epoxy resins (D‐LCERDP). D‐LCERDP‐10.0 (10.0 wt% DP) synchronously possesses excellent intrinsic thermal conductivity and intrinsic flame retardancy, with thermal conductivity coefficient in vertical and parallel direction (λ⊥ and λ∥) of 0.34 and 1.30 W m−1 K−1, much higher than that of general bisphenol A epoxy resin (E‐51, λ⊥ of 0.19 W m−1 K−1, λ∥ of 0.65 W m−1 K−1). The limiting oxygen index (LOI) value of D‐LCERDP‐10.0 reaches 31.1, also better than those of E‐51 (19.8) and D‐LCER (21.3). [ABSTRACT FROM AUTHOR]

P‐stereogenic tert‐ and sec‐phosphines have wide applications in asymmetric catalysis, materials, and pharmaceutical chemistry, however, their practical synthesis still constitutes a significant challenge. Herein, a successful kinetic resolution of rac‐secondary phosphine oxides via the enantioselective P‐benzylation process catalyzed by the palladium/Xiao‐Phos was designed. Both tert‐ and sec‐phosphine oxides were delivered in good yield and excellent enantiopurity (selectivity factor up to 226.1). The appealing synthetic utilities are further demonstrated by the facile preparation of several valuable P‐chiral compounds, precursors of bidentate ligands, as well as transition metal complexes. [ABSTRACT FROM AUTHOR]

An inverse‐electron‐demand Diels–Alder (IEDDA) reaction could complement the conventional normal‐electron‐demand Diels–Alder reaction in the synthesis of six‐membered carbocycles. However, catalytic asymmetric all‐carbon‐based IEDDA reactions are underdeveloped. Herein, we disclosed a copper‐catalyzed asymmetric IEDDA reaction using electron‐deficient 3‐carboalkoxyl‐2‐pyrones and electronically unbiased indenes as reactants. This method enables the rapid and enantioselective construction of a wide range of hexahydrofluorenyl bridged‐lactone scaffolds. Using this method, asymmetric total syntheses of cephanolides A and B were accomplished. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A highly enantioselective palladium‐catalyzed intermolecular tandem Heck/Cacchi reaction of unactivated alkenes with ortho‐ethynylanilines was developed, which provides a powerful route to access a broad range of enantioenriched 2,3‐dihydrobenzofuran‐ or indoline‐substituted indoles bearing all‐carbon quaternary stereocenter of interest in pharmaceutical research. Its salient features include inherent atom‐ and step‐economy, high functional group tolerance, mild conditions, broad structural diversity together with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

Despite much progress has been made in the asymmetric α‐arylation reactions of cyclic ketones, lactones and lactams, the enantioselective α‐arylation of acyclic carbonyl compounds lagged much behind due to the in situ generated Z/E‐enolate intermediates leading to opposite enantiomers. Especially, the asymmetric α‐arylation of acyclic aldehydes is a long‐standing challenge, because of the highest activity among carbonyl compounds leading to various competitive side reactions. Herein we reported an efficient Pd‐catalyzed asymmetric intermolecular α‐arylation reaction of α‐alkyl‐α‐aryl disubstituted aldehydes with aryl bromides, which provides a rapid access to chiral aldehydes bearing an α‐all‐carbon quaternary stereocenter in moderate to good yields with good er in most cases. In addition, a pair of enantiomers could be easily prepared with the use of the same ligand by exchanging the aryl groups of aldehyde and aryl bromide. [ABSTRACT FROM AUTHOR]

Although tremendous efforts have been devoted into research and development of materials science and engineering, chemistry, electrochemistry, and solid‐state physics in lithium‐ion batteries (LIBs) over the last 30 years, the critical technologies and applied science underneath manufacturing and processing seem very seldom reported, which is further manifested by the realization of the gap between academy and industry within recent years. In this paper, the intrinsic relationship of materials‐processing‐performance is highlighted by thoroughly reviewing the bridge effect of processing, transport, and transfer at different scales across electrode, heterogeneous thermodynamics, and kinetics during charge‐discharge cycles, the tradeoff between areal capacity and rate performance, and some practical novel electrode designs. Based on very limited open literature, the fundamental basics and sciences of the state of art production steps including slurry mixing, coating, drying, calendering, electrolyte filling, and formatting are comprehensively discussed. Through correlating with the materials design and development, the electrode compositions and structures, and the bridge effect of processing, the in‐depth understanding of the importance of individual steps and their interactions are provided to shed light on further improvement on materials and manufacturing for LIBs. [ABSTRACT FROM AUTHOR]

Most of the ancient buildings are made of inflammable wooden structures, which have serious potential safety hazards. Applying fire‐retardant coating is one of the simplest and most effective means of fire prevention in ancient wooden buildings. In this work, we have demonstrated that the Ti3C2Tx transition metal carbide/carbonitride (MXene) was applied as the synergetic agent, waterborne epoxy resin as the film‐forming agent, ammonium polyphosphate, dipentaerythritol, and melamine (P‐C‐N system) as the intumescent fire‐retardant system to prepare Ti3C2Tx/epoxy intumescent fire‐retardant coating (TEIFC). The results showed that MXene has significantly improved the fire‐retardant performance of the coating. By incorporating 3 wt% Ti3C2Tx (TEIFC‐3, with 62 wt% P‐C‐N system), the coating displayed UL‐94 V‐0 rating with the limiting oxygen index value of 38%. In addition, the combination of Ti3C2Tx and P‐C‐N system enhanced the Shore hardness of the coating to 95 SHD (TEIFC‐3). Furthermore, TEIFC‐3 presented high thermal stability with the THRI of 177.0°C and Tdmax of 380.5°C. This work provides a novel strategy for the design and preparation of intumescent fire‐retardant coating, which will greatly broaden the industrial applications of MXene‐based polymer composites in the field of fire prevention of ancient buildings. [ABSTRACT FROM AUTHOR]

RATIONALE: Gas chromatography mass spectrometry (GC‐MS) with electron ionization (EI) is the most widely used analysis technique of gaseous samples, but it may be time‐consuming for online monitoring of mixtures whose concentrations relatively change rapidly. On the contrary, current ionization methods, such as chemical ionization (CI) and proton transfer reaction (PTR), also have some disadvantages such as selectivity. Therefore, appropriate soft ionization sources are searched for rapid online detection. METHODS: Hollow electrode capillary plasma ionization (HECPI) is based on single electrode plasma. A hollow capillary was placed as both the electrode and the inlet of the gaseous samples. The ionization source is coupled with a mass spectrometer for performance evaluation. RESULTS: Several typical compounds have been tested with HECPI‐mass spectrometer. In this process, the dominant ion peaks of all compounds can be indexed as molecular ion peaks, and the product ions of HECPI are less than that of dielectric barrier discharge ionization (DBDI). Three gaseous samples (linalool, triethylamine, and styrene) with various concentrations have been used to further confirm the performance of this source, and the detection limit of linalool is as low as 10 ppb. CONCLUSIONS: HECPI is simple in structure and shows good performance. The results also show that HECPI has the potential to be an effective tool for detecting online gaseous samples rapidly. [ABSTRACT FROM AUTHOR]

Herein, a Brønsted acid‐catalyzed C(sp2)−H functionalization of free phenols with 1,3‐dienes has been developed. In this transformation, triflic acid promoted C−H bond functionalization under mild conditions in a site‐selective manner. [ABSTRACT FROM AUTHOR]

Single atom catalysts (SACs) show a great attraction towards the oxygen reduction reaction (ORR) owing to its advantage in overcoming the cost issue of fuel cell because of its high utilization, low cost and great CO tolerance. However, theoretical investigation on the influences of different doping on the ORR catalytic activity of Co SACs has not been systematically performed. In this regard, the influences of non‐metal‐elements doping (B, N, Si, P, S) on the ORR catalytic activity of Co−gN4 is well explored based on density functional theory (DFT). The rate‐limiting step for the ORR on Co−gN4 is the formation of OOH. When the doping content of B increases, the adsorption on Co site becomes weaker which limits the occurrence of 4e− ORR process. N doping shows a weak promotion on the ORR process on Co site. The Si site next to N can be poisoned by OH. The P site next to N will be poisoned by O at high potential and OH at low potential. The S site next on N would be poisoned by O. It is revealed that the ORR process on Co site can be promoted when the carbon next to N is replaced by Si/P/S by promoting the rate‐limiting step. [ABSTRACT FROM AUTHOR]

A series of copolymers containing 50 mol % acrylic acid (AA) and 50 mol % butyl acrylate (BA) but with differing composition profiles ranging from an AA‐BA diblock copolymer to a linear gradient poly(AA‐grad‐BA) copolymer were synthesized and their pH‐responsive self‐assembly behavior was investigated. While assemblies of the AA‐BA diblock copolymer were kinetically frozen, the gradient‐like compositions underwent reversible changes in size and morphology in response to changes in pH. In particular, a diblock copolymer consisting of two random copolymer segments of equal length (16 mol % and 84 mol % AA content, respectively) formed spherical micelles at pH >5, a mix of spherical and wormlike micelles at pH 5 and vesicles at pH 4. These assemblies were characterized by dynamic light scattering, cryo‐transmission electron microscopy and small angle neutron scattering. [ABSTRACT FROM AUTHOR]

Eine Serie von Copolymeren, die 50 % Acrylsäure (AA) und 50 % Butylacrylat (BA) enthielten, jedoch unterschiedliche Zusammensetzungsprofile aufwiesen, wurden synthetisiert und ihr pH‐abhängiges Selbstassemblierungsverhalten untersucht. Dabei reichten die synthetisierten Profile von einem AA‐BA‐Diblockcopolymer bis zu einem Poly(AA‐grad‐BA)‐Copolymer mit linearem Gradienten. Während assemblierte Gruppen des AA‐BA‐Diblockcopolymers kinetisch gehemmt waren, zeigten die gradientenartigen Kompositionen reversible Änderungen der Größe und Morphologie als Reaktion auf Veränderung des pH‐Werts. Im Speziellen bildete ein Diblockcopolymer, das aus zwei ungeordneten Copolymersegmenten gleicher Länge (16 % bzw. 84 % AA‐Gehalt) bestand, kugelförmige Mizellen bei einem pH‐Wert >5, eine Mischung aus kugelförmigen und wurmartigen Mizellen bei pH 5 und Vesikel bei pH 4. Diese Anordnungen wurden durch dynamische Lichtstreuung (DLS), Kryo‐Transmissionselektronenmikroskopie (Kryo‐TEM) und Kleinwinkelneutronenstreuung (SANS) charakterisiert. [ABSTRACT FROM AUTHOR]

The first example of highly enantioselective fluoroarylation of gem‐difluoroalkenes with aryl halides is presented by using a new chiral sulfinamide phosphine (Sadphos) type ligand TY‐Phos. N‐Me‐TY‐Phos can be easily synthesized on a gram scale from readily available starting materials in three steps. Salient features of this work including readily available starting materials, good yields, high enantioselectivities as well as broad substrate scope make this approach very practical and attractive. Notably, the asymmetric synthesis of an analogue of a biologically active molecule is also reported. [ABSTRACT FROM AUTHOR]

A palladium‐catalyzed intermolecular dynamic kinetic asymmetric dearomatization of 3‐arylindoles with internal alkynes was developed with the use of achiral Xantphos and chiral sulfinamide phosphine ligand (PC‐Phos) as the co‐ligands. This method could deliver various spiro[indene‐1,3′‐indole] compounds in good yields (up to 95 % yield) with up to 98 % ee. The salient features of the transformation include the use of readily available substrates, ease of scale‐up and the versatile functionalization of the products. The mechanistic experiments gave some insights on active intermediates. [ABSTRACT FROM AUTHOR]

Alkenylphosphine oxides have a wide spectrum of practical applications. However, chemo‐, regio‐, and enantiocontrolled construction of this structural motif still constitutes a significant synthetic challenge. Here we show that these compounds can be efficiently accessed by using a palladium/Xiao‐Phos catalytic system, which leads to the highly regioselective formation of the anti‐Markovnikov adducts through addition of a secondary phosphine oxide to an alkyne. Diverse (hetero)aryl and alkyl alkynes, as well as both terminal and internal alkynes can be employed as substrates. The kinetic resolution process makes it possible to produce alkenylphosphine oxide and recovered secondary phosphine oxides with high ee values. Further transformations of these two P‐chiral scaffolds confirm the high practicability and application prospect of our synthetic strategies. Initial mechanistic studies strongly suggested that hydropalladation is likely responsible for the conversion process. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A visible light driven Cu(I)‐catalyzed intermolecular oxyamination of electron‐deficient olefins has been achieved by using O‐benzoylhydroxylamines as donors both for amine and oxygen. The transformation properties afford mild conditions and a wide substrate scope, providing access to ester derivatives of β‐amino alcohols with good yields and high regioselectivity. [ABSTRACT FROM AUTHOR]

During the past few decades, there has been considerable growth in the development of denitrogenative reactions of triazole skeletons to construct valuable cyclic compounds, particularly heterocycles. Despite the inherent difficulty of the ring‐opening of triazole derivatives, many novel and efficient approaches have arisen in this area mainly with the use of transition metal (such as rhodium, palladium, silver, copper) catalysis, photolysis, or free radical mediated reactions. Generally, these procedures begin with the ring‐opening of 1,2,3‐triazoles or benzotriazoles followed by N2 extrusion and subsequent diverse transformations, which enable the rapid synthesis of various heterocycles in a single step. To avoid overlap with other related reviews, this minireview covers the recent advances in the denitrogenative cyclization of 1,2,3‐triazoles since 2016 and the denitrogenative cyclization of benzotriazoles since 2012. [ABSTRACT FROM AUTHOR]

BACKGROUND Dehydroepiandrosterone (DHEA), a steroid hormone drug and a precursor of other steroid hormone drugs, is industrially important. We aimed to establish the co‐immobilization of keto reductase and glucose dehydrogenase by a crosslinked enzyme aggregate (co‐CLEA) and to determine whether co‐CLEAs can improve DHEA yield compared with crude enzymes. RESULTS: Heterologous expression plasmids containing genes coding for keto reductase or glucose dehydrogenase were constructed. The size of each of these proteins was determined using SDS‐PAGE and purification on a nickel column. After optimizing the expression conditions for these two enzymes, the co‐CLEAs were prepared with 80% acetone as a precipitant and 0.005% glutaraldehyde as a crosslinking agent. Compared with the crude enzyme solutions, the co‐CLEAs showed better thermal stability and pH stability. After six cycles of use, the co‐CLEAs still showed 70% (keto reductase) and 46% (glucose dehydrogenase) of their initial activities. After four reaction cycles, the accumulated production of DHEA using the co‐CLEAs reached 183 g L–1. CONCLUSIONS: This research provides a possible strategy for the production of clinically useful DHEA through co‐immobilization. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Ordered mesoporous SBA‐15 supported chiral phosphine gold (I) complexes were successfully developed. The gold(I) complexes were covalently immobilized on mercaptopropyl modified SiO2 surface through radical reaction. In this way, the chiral carbon and chiral sulfur of the homogenous catalyst were perfectly remained in situ. And thus, the prepared catalysts demonstrated highly effective asymmetric cycloaddition activity, which was likely because the chiral induction effect of the Au complex was hardly influenced by this immobilization method. Moreover, they could be easily recovered by simple filtration and directly used for the subsequent catalytic runs. The prepared catalyst was highly stable and efficient without obvious activity loss after eight cycles. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A gold(I)‐catalyzed asymmetric intermolecular tandem [3+3]‐cyclization reaction of 2‐(1‐alkynyl)‐2‐ alken‐1‐ones with nitrones has been developed by using Ming‐Phos as a chiral ligand. This method enables access to the stereodivergent synthesis of highly substituted furo[3,4‐d][1,2]oxazines in excellent efficiency and stereoselectivity (up to 99% yield, 99% ee, >20 : 1 dr). [ABSTRACT FROM AUTHOR]

Lithium ion batteries (LIBs) continuously prove themselves to be the main power source in consumer electronics and electric vehicles. To ensure environmental sustainability, LIBs must be capable of performing well at extreme temperatures, that is, between −40 and 60 °C. In this review, the recent important progress and advances in the subzero and elevated temperature operations of LIBs is comprehensively summarized from a materials perspective. In the scenario of subzero temperatures, limitations, electrolytes, anodes, and solid electrolyte interphase (SEI); cathodes and cathode electrolyte interphase (CEI); and binders are thoroughly discussed to explore the fundamentals and basics that underlie the decay in electrochemical performance and how the chemistry, physics, and electrochemistry are correlated with the materials and components that interact with each other. In the case of high temperatures limitations, the thermal stability of the key materials and components are reviewed, and then the reaction thermodynamics and kinetics of the anodes, cathodes, electrolytes, and their interactions are described using the highest occupied molecular orbit (HOMO)/lowest unoccupied molecular orbit (LUMO), and are extensively discussed. The prospect of combining the extreme temperature poles in a single cell by introducing appropriate electrolytes and additives is discussed. [ABSTRACT FROM AUTHOR]

Reported here is a highly efficient Pd/Xiang‐Phos catalyzed enantioselective carboetherification of alkenyl oximes with either aryl or alkenyl halides, delivering various chiral 3,5‐disubstituted and 3,5,5‐trisubstituted isoxazolines in good yields with up to 97 % ee. The sterically bulky and electron‐rich (S,Rs)‐NMe‐X2 ligand is responsible for the excellent reactivities and enantioselectivities. The salient features of this transformation include mild reaction conditions, general substrate scope, good functional‐group tolerance, good yields, high enantioselectivities, easy scale‐up, and application in the late‐stage modification of bioactive compounds. The obtained products can be readily transformed into useful chiral 1,3‐aminoalcohols. [ABSTRACT FROM AUTHOR]

Sonogashira‐type cross‐couplings are one of the most significant alkynylations in organic chemistry. One of the first palladium‐catalyzed intramolecular Heck/Sonogashira reactions of alkenes with terminal alkynes is now reported. With this method, a variety of uniquely substituted chiral benzene‐fused heterocycles bearing a propargyl‐substituted all‐carbon quaternary stereocenter were obtained in a straightforward, high‐yielding, and highly stereoselective manner under mild conditions. Salient features of this process include the use of readily available substrates, high selectivities, a broad substrate scope as well as versatile product functionalizations. [ABSTRACT FROM AUTHOR]

A highly enantioselective dicarbofunctionalization of unactivated alkenes was implemented by a Pd‐catalyzed asymmetric tandem Heck/Suzuki coupling reaction. This reaction represents the first example of a highly enantioselective intramolecular cyclization/cross‐coupling of olefin‐tethered aryl halides with alkyl‐, alkenyl‐ or arylboronic acids, and provides rapid access to a number of chiral compounds, such as dihydrobenzofurans, indolines, chromanes, and indanes bearing a quaternary stereocenter, in good yields with excellent enantioselectivities. The practicality of this reaction was validated in the modification of biologically complex molecules such as peptides, piperitol, CB2 receptor agonists, etc. Moreover, the synthesis of two enantiomers can be easily realized by simple change in the order of the steps in the coupling sequence. [ABSTRACT FROM AUTHOR]

It is critical to develop a highly effective and economical electrocatalyst to lower the energy losses for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In this work, Fe‐doped Ni3S2 nanowires with diameters of ca. 17 nm and lengths of 1.4∼2 μm are synthesized on Ni foam through a one‐step solvothermal route for alkaline water splitting, which display notable active and excellent durability for both OER and HER under high current densities. The optimal Fe13.7%‐Ni3S2 nanowires electrode can attain 200 mA cm−2 at a fairly low overpotential of 223 mV, and 500 mA cm−2 at 245 mV toward OER. Furthermore, it yields a considerable low overpotential of 109 mV to garner 10 mA cm−2, and 246 mV for 500 mA cm−2 toward HER. The incorporation of iron simultaneously modifies the electronic structure and morphology of Ni3S2, which not only enhances the conductivity but also generates abundant active edge sites. The slight surface‐restricted oxidation of nanowires in a strongly basic electrolyte in situ generates a large number of interfaces, which enables the reactivity and durability for both OER and HER. Accordingly, an alkaline water electrolyzer with two Fe13.7%‐Ni3S2 electrodes only requires a low cell voltage of 1.53 V to achieve 10 mA cm−2, and 1.95 V to 500 mA cm−2 with striking stability. The as‐prepared Fe‐doped Ni3S2 nanowires can be potentially utilized for actual water electrolysis under high current densities. [ABSTRACT FROM AUTHOR]

Reported herein is an asymmetric Pd/PC‐Phos‐catalyzed denitrogenative cyclization of benzotriazoles with allenes and N‐allenamides, representing the first example of enantioselective denitrogenative cyclizations of benzotriazoles. A series of optically active 3‐methyleneindolines were obtained in good yields with high ee values. The use of inexpensive and readily available starting materials, high regio‐ and enantioselectivity, a broad substrate scope, mild reaction conditions, no need for base, as well as versatile functionalization of the 3‐methyleneindolines make this approach attractive. [ABSTRACT FROM AUTHOR]

Over the past years, the metal‐catalyzed dearomative cycloaddition of 3‐nitroindoles and 2‐nitrobenzofurans have emerged as a powerful protocol to construct chiral fused heterocyclic rings. However, organocatalytic dearomative reaction of these two classes of heteroarenes has become a long‐standing challenging task. Herein, we report the first example of phosphine‐catalyzed asymmetric dearomative [3+2]‐cycloadditio of 3‐nitroindoles and 2‐nitrobenzofurans, which provide a new, facile, and efficient protocol for the synthesis of chiral 2,3‐fused cyclopentannulated indolines and dihydrobenzofurans by reacting with allenoates and MBH carbonates, respectively through a dearomative [3+2]‐cycloaddition. The first example of phosphine‐catalyzed asymmetric dearomative [3+2]‐cycloaddition of 3‐nitroindoles and 2‐nitrobenzofurans was realized, which provides a new, facile, and efficient protocol for the synthesis of chiral 2,3‐fused cyclopentannulated indolines and dihydrobenzofurans by reacting with allenoates and MBH carbonates, respectively. [ABSTRACT FROM AUTHOR]

Chiral dihydrobenzofuran units are frequently present in molecules with significant biological and pharmaceutical activities. Herein, we present the first enantioselective formal [4+1] annulation of Morita‐Baylis‐Hillman carbonates with o‐quinone methides (o‐QMs) catalyzed by a newly designed chiral phosphine catalyst. Under the mild and eco‐friendly conditions, a wide range of polysubstituted dihydrobenzofurans were obtained in good yields with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

An efficient and practical phosphine‐catalyzed vicinal difunctionalization of β‐fluoroalkyl α,β‐enones with TMSN3 has been developed. Using dppb as the catalyst, the reaction worked efficiently to yield various β‐amino α‐diazocarbonyl compounds in high yields (up to 94 %). This work marks the first efficient construction of α‐diazocarbonyl compounds by phosphine catalysis. Meanwhile, the asymmetric variant induced by the nucleophilic bifunctional phosphine P4 led to various chiral fluoroalkylated β‐amino α‐diazocarbonyl compounds in high yields and enantioselectivity. NMR and ESI‐MS studies support the existence of the key reaction intermediates. In contrast, β‐azide carbonyl compounds would be furnished in good yields from β‐fluoroalkylated β,β‐disubstituted enones. An efficient and practical phosphine‐catalyzed vicinal difunctionalization of β‐fluoroalkyl α,β‐enones with TMSN3 has been developed. Meanwhile, the asymmetry variant induced by the nucleophilic bifunctional phosphine P4 led to various chiral fluoroalkylated β‐amino α‐diazocarbonyl compounds in high yields and enantioselectivity. [ABSTRACT FROM AUTHOR]