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Nitric oxide (NO) and NO–water clusters play crucial roles in the D-region of the atmosphere because it is postulated that NO+ reacts with H2O to produce nitrous acid (HONO) and H3O+. HONO is the major precursor of the hydroxyl radicals leading to the formation of secondary pollutants. The sources of atmospheric HONO, however, are not fully understood. Previously, the sequential H2O addition reaction, H2O + NO+(H2O)n, and the bi-molecular collision reaction, NO+ + (H2O)n, have been investigated by both experiments and theoretical calculations to determine the formation mechanism of HONO. However, the photo-reactions from NO(H2O)n neutral clusters were not considered for the formation mechanism of HONO. In this study, the intra-cluster reactions of NO+(H2O)n clusters, following ionization of the parent neutral cluster of NO(H2O)n, were investigated using the direct ab initio molecular dynamics method. When n = 4, [NO+(H2O)4]ver [vertical ionization state of NO(H2O)n] yielded HONO and hydrated H3O+ after the intra-cluster reaction, and the reaction time was calculated to be 150 fs. The reaction is expressed as [NO+(H2O)n]ver → HONO + H3O+(H2O)n−2 (reactive) (n > 3). Larger clusters of [NO+(H2O)n]ver (n = 5–8) also yield HONO. In contrast, in smaller clusters (n = 1–3), only solvent re-orientation around NO+ occurred after the ionization: [NO+(H2O)n]ver → NO+(H2O)n (solvent re-orientation) (n = 1–3). The hydration energy of H3O+, which depends on the cluster size (n), plays an important role in promoting the formation of HONO. The reaction mechanism is discussed based on theoretical results. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) and NO–water clusters play crucial roles in the D-region of the atmosphere because it is postulated that NO+ reacts with H2O to produce nitrous acid (HONO) and H3O+. HONO is the major precursor of the hydroxyl radicals leading to the formation of secondary pollutants. The sources of atmospheric HONO, however, are not fully understood. Previously, the sequential H2O addition reaction, H2O + NO+(H2O)n, and the bi-molecular collision reaction, NO+ + (H2O)n, have been investigated by both experiments and theoretical calculations to determine the formation mechanism of HONO. However, the photo-reactions from NO(H2O)n neutral clusters were not considered for the formation mechanism of HONO. In this study, the intra-cluster reactions of NO+(H2O)n clusters, following ionization of the parent neutral cluster of NO(H2O)n, were investigated using the direct ab initio molecular dynamics method. When n = 4, [NO+(H2O)4]ver [vertical ionization state of NO(H2O)n] yielded HONO and hydrated H3O+ after the intra-cluster reaction, and the reaction time was calculated to be 150 fs. The reaction is expressed as [NO+(H2O)n]ver → HONO + H3O+(H2O)n−2 (reactive) (n > 3). Larger clusters of [NO+(H2O)n]ver (n = 5–8) also yield HONO. In contrast, in smaller clusters (n = 1–3), only solvent re-orientation around NO+ occurred after the ionization: [NO+(H2O)n]ver → NO+(H2O)n (solvent re-orientation) (n = 1–3). The hydration energy of H3O+, which depends on the cluster size (n), plays an important role in promoting the formation of HONO. The reaction mechanism is discussed based on theoretical results. [ABSTRACT FROM AUTHOR]

Reactive melt infiltration (RMI) is a typical method to produce carbon fiber-reinforced ultra-high temperature ceramic matrix composites (C f /UHTCs), for which the molten Si is a very general and practical infiltrator. High-entropy carbide (HE-carbide) is a newly developed promising matrix phase of C f /UHTCs. Understanding the phase equilibrium relation in the HE-carbide and Si reaction system can provide accurate guidance on designing the RMI process for preparing HE-carbide matrix composites with controlled phases and microstructure. This study systematically investigates W-containing HE-carbide and Si addition reactions at high temperatures. Samples with nominal starting compositions of (Ti 0. 2 Zr 0.2 Hf 0.2 Ta 0. 2 W 0.2)C- x Si (HEC- x Si, x = 2.5, 5 and 10 wt%) are prepared by spark plasma sintering technique at 1500 °C and 1700 °C with an axial pressure of 40 MPa for 10 min. The results show that adding 2.5 wt% or 5 wt% Si removes carbon from the HEC matrix, forming SiC and stable equimolar (Ti 0. 2 Zr 0.2 Hf 0.2 Ta 0. 2 W 0.2)C 1- x phase with carbon deficiency at high temperatures. In contrast, besides the SiC phase, the addition of 10 wt% Si in the HEC matrix may form unstable transient phases of (Ti 0. 2 Zr 0.2 Hf 0.2 Ta 0. 2 W 0.2)C 1- x with supersaturated carbon deficiencies at high temperatures, which finally decomposes into non-equimolar HE-carbide (Ti 0. 2 Zr 0.2 Hf 0.2 Ta 0. 2 W 0.2- y)C 1- z and metal silicide WSi 2 phases. The effects of the HEC and Si reactions on the microstructure evolution of the samples during sintering are discussed. Meanwhile, the mechanical properties of the samples with the reaction resulting microstructure are measured and briefly discussed. [ABSTRACT FROM AUTHOR]

An increased intracellular Ca2+ concentration ([Ca2+]i) is a key trigger for pulmonary arterial smooth muscle cell (PASMC) proliferation and contributes greatly to pulmonary hypertension (PH). Extracellular Ca2+ influx via a store-operated Ca2+ channel, termed store-operated Ca2+ entry (SOCE), is a crucial mechanism for [Ca2+]i increase in PASMCs. Calcium release–activated calcium modulator (Orai) proteins, consisting of three members (Orai1–3), are the main components of the store-operated Ca2+ channel. Sodium houttuyfonate (SH) is a product of the addition reaction of sodium bisulfite and houttuynin and has antibacterial, antiinflammatory, and other properties. In this study, we assessed the contributions of Orai proteins to monocrotaline (MCT)–enhanced SOCE, [Ca2+]i, and cell proliferation in PASMCs and determined the effect of SH on MCT-PH and the underlying mechanism, focusing on Orai proteins, SOCE, and [Ca2+]i in PASMCs. Our results showed that: 1) Orai1 and Orai2 were selectively upregulated in the distal pulmonary arteries and the PASMCs of MCT-PH rats; 2) knockdown of Orai1 or Orai2 reduced SOCE, [Ca2+]i, and cell proliferation without affecting their expression in PASMCs in MCT-PH rats; 3) SH significantly normalized the characteristic parameters in a dose-dependent manner in the MCT-PH rat model; and 4) SH decreased MCT-enhanced SOCE, [Ca2+]i, and PASMC proliferation via Orai1 or Orai2. These results indicate that SH likely exerts its protective role in MCT-PH by inhibiting the Orai1,2–SOCE–[Ca2+]i signaling pathway. [ABSTRACT FROM AUTHOR]

The mechanochromic materials can respond to environmental changes by altering the optical properties of the system, which has garnered significant attention in recently. The utilization of these materials for the purpose of sensing tensile and compressive stress has been extensively documented. However, the mechanochromic polymer that can effectively discriminate hardness of inorganic particles is still rarely reported. In this article, a force‐sensitive organic polysiloxane was developed by introducing triethenyl‐substituted rhodamine derivatives crosslinker into the polymethylhydrosiloxane network through hydrosilylation addition reaction. The results demonstrated that the grinding of the crosslinked polysiloxane effectively facilitated the transmission of external force to the polymeric network, leading to an open ring isomerization of rhodamine accompanied by significant alterations in visible and fluorescent color. In addition, we found that the optical properties of the system showed distinct variations when the inorganic particles with different Moh's hardness were co‐ground with the polysiloxane. High Moh's hardness particles, such as Al2O3, could effectively trigger the mechanochromic behavior of the polymer, while Na2SO4 particles with low hardness failed to induce the corresponding change. Therefore, this organic polysiloxane could be used as a potential fluorescent indicator for hardness recognition. [ABSTRACT FROM AUTHOR]

ABSTRACT Methotrexate (MTX) is a chemotherapy agent and immune system suppressant that is widely used to treat a variety of malignant and nonmalignant diseases. Due to some drawbacks of the existing methods for the determination of MTX in aquatic and real samples, we prepared a new, simple, and selective dual‐mode fluorometric and electrochemical approach based on peroxidase‐mimic [Mo36] polyoxomolybdate nanoclusters (POMo) for sensing MTX. A turn‐on–off fluorometric approach for the detection of MTX was developed, which was based on the inhibition of the emission intensity of the terephthalic acid (TA)‐H2O2 system upon the addition of MTX to the reaction solution. The electrocatalytic performance of the obtained POMo was studied after making a carbon paste electrode (CPE) utilizing cyclic voltammetry and amperometry analysis. Under the optimum condition, good linearity was observed between the quenched emission intensity of the system and MTX dosage in the range of 0.5–250 μM with a limit of detection (LOD) of 0.91 μM. The electrochemical method illustrated a much better response with an extensive linear range of 0.01–475 μM and a lower LOD (1.61 nM). Analytical recoveries and RSD% values were, respectively, in the range of 87.72%–110% and 0.33%–1.32% for the fluorometric system and 96%–106% and 0.77%–1.02% for the electrochemical platform. Finally, the selectivity of the sensor was evaluated against various common interfering species, and the results indicated satisfactory selectivity of the POMo dual‐mode system towards MTX. [ABSTRACT FROM AUTHOR]

The Ni‐catalyzed enantioselective addition reaction of aryl halides to aldehydes was studied with cyanobis(oxazoline) as chiral ligands and Mn as reductant. Aryl and heteroaryl bromides reacted with phenyl aldehyde at room temperature to produce dibenzyl alcohols in 16–99 % yields with 53–92 % ees. Moreover, the coupling of phenyl chloride with a variety of aryl, heteroaryl and alkyl aldehydes was demonstrated in the presence of cyanobis(oxazoline)/Ni(II) at 60 °C in generally high yields with moderate enantioselectivities. [ABSTRACT FROM AUTHOR]

Alkyl chlorides are a class of versatile building blocks widely used to generate C(sp3)‐rich scaffolds through transformation such as nucleophilic substitution, radical addition reactions and metal‐catalyzed cross‐coupling processes. Despite their utility in the synthesis of high‐value functional molecules, distinct methods for the preparation of alkyl chlorides are underrepresented. Here, we report a visible‐light‐mediated dual catalysis strategy for the modular synthesis of highly functionalized and structurally diverse arylated chloroalkanes via the coupling of diaryliodonium salts, alkenes and potassium chloride. A distinctive aspect of this transformation is a ligand‐design‐driven approach for the development of a copper(II)‐based atom‐transfer catalyst that enables the aryl‐chlorination of electron‐poor alkenes, complementing its iron(III)‐based counterpart that accommodates non‐activated aliphatic alkenes and styrene derivatives. The complementarity of the two dual catalytic systems allows the efficient aryl‐chlorination of alkenes bearing different stereo‐electronic properties and a broad range of functional groups, maximizing the structural diversity of the 1‐aryl, 2‐chloroalkane products. [ABSTRACT FROM AUTHOR]

We report the addition reaction of lithium enol ethers to fluoroalkyl imines. A range of different fluoroalkyls and lithiated reagents are well tolerated. Diastereoselective addition of lithium vinyl ethers to fluoroalkyl N‐tert‐butylsulfinylimines is disclosed, providing enantiomerically enriched α‐fluorinated amines in up to 98% yield. This general approach led to the diastereoselective formation of various amino alcohols and amino ethers, which are difficult to obtain by other methods. [ABSTRACT FROM AUTHOR]

AbstractQuinolines are very important materials in organic synthesis due to their wide range of biological activities as well as representing one of the most research area in medicinal chemistry. Quinolines have many applications in design and synthesis of multiple heterocyclic compounds with a wide variety of biological significance. Quinolines fused heterocycles at face b using different synthetic methodologies as well as variable precursors and reaction conditions were the aim of the current review. [ABSTRACT FROM AUTHOR]

A dual cooperative multi‐urea catalyst for Henry reaction was developed in which four urea groups were introduced into a rigid and rotatable framework. The tetraurea catalyst 1 showed higher activity for Henry reaction than its analogues, close‐bisurea 2 or distal‐bisurea 3 with two urea units, demonstrating additional cooperativity between the two substrate‐pinching catalytic sites of tetraurea 1. Addition of the reaction product to the reaction system resulted in a small amount of further activation. This work would provide a basis for new cooperative molecular catalysts, leading to a high degree of regulation based on allosteric cooperativity, e.g. with a distinct ON/OFF threshold for reactivity, or feedback activation by using the product as a reaction template. [ABSTRACT FROM AUTHOR]

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N-Furfuryl allylamines react with a broad range of isocyanates, isothiocyanates, isoselenocyanates with the formation of a 3a,6-epoxyisoindole core in one synthetic stage. The interaction sequence involves two consecutive steps: the nucleophilic addition reaction and the intramolecular Diels–Alder furane (IMDAF) reaction. The scope and limitations of the proposed method were thoroughly investigated, and it was revealed that the key [4+2] cycloaddition step proceeds through an exo-transition state, giving rise to the exclusive formation of a single diastereomer of the target heterocycle. Dynamic temperature NMR analysis allowed to fully investigating a case of coalescence of NMR signals and determined the coalescence temperature during the transition O → Se. The antimicrobial properties of the obtained compounds against sensitive strains of yeast Candida albicans, fungus Aspergillus niger and bacteria including Staphylococcus aureus, Micrococcus luteus, Pseudomonas fluorescens were identified. [ABSTRACT FROM AUTHOR]

Two‐electron oxidative addition is one of the most important elementary reactions for d‐block transition metals but it is uncommon for f‐block elements. Here, we report the first examples of intermolecular oxidative addition of E−H (E=C, N) bonds to uranium(II) centers. The transient U(II) species was formed in‐situ by reducing a heterometallic cluster featuring U(IV)‐Pd(0) bonds with potassium‐graphite (KC8). Oxidative addition of C−H or N−H bonds to the U(II) centers was observed when this transient U(II) species was treated with benzene, carbazole or 1‐adamantylamine, respectively. The U(II) centers could also react with tetracene, biphenylene or N2O, leading to the formation of arene reduced U(IV) products and uranyl(VI) species via two‐ or four‐electron processes. This study demonstrates that the intermolecular two‐electron oxidative addition reactions are viable for actinide elements. [ABSTRACT FROM AUTHOR]

The reactivity of imidazole, pyrazole, 1,2,4‐triazole, 1,2,3‐triazole, and tetrazole with acetone (propan‐2‐one) has been studied by 1H and 13C NMR using acetone‐d6 as solvent at temperatures ranging from 173 to 300 K at 10 K intervals. Simultaneously, the reaction has been theoretically calculated at the B3LYP/6‐311++G(d,p) level, and experimental and theoretical results have been compared. The equilibrium constants between azoles and adducts α,α‐dimethyl‐azole‐methanol were analyzed, assuming that the straight part of the plots –R ln Ke vs. 1/T can be used to determine ΔH and ΔS. Calculated and experimental data are related, but the theoretical values are proportionally higher. The tautomerism of triazoles and tetrazole has been considered in order to discuss the reactions. [ABSTRACT FROM AUTHOR]

Ni‐catalyzed activation of C(sp2)−H bond remains an elusive challenge. Herein, we realized a Ni‐catalyzed selective activation of C(sp2)−H bond of formamides, which underwent addition reaction with internal alkynes to provide α,β‐unsaturated amide compounds in high yields. The protocol was featured by the cheap and nontoxic catalyst system. Preliminary mechanistic studies shed light on the reaction pathways. [ABSTRACT FROM AUTHOR]

Organic fluorides are widely used in pharmaceuticals, agrochemicals, material sciences, and other fields due to the special physical and chemical properties of fluorine atoms. The synthesis of alkyl fluorinated compounds bearing multiple contiguous stereogenic centers is the most challenging research area in synthetic chemistry and has received extensive attention from chemists. This review summarized the important research progress in the field over the past decade, including asymmetric electrophilic fluorination and the asymmetric elaboration of fluorinated substrates (such as allylic alkylation reactions, hydrofunctionalization reactions, Mannich addition reactions, Michael addition reactions, aldol addition reactions, and miscellaneous reactions), with an emphasis on synthetic methodologies, substrate scopes, and reaction mechanisms. [ABSTRACT FROM AUTHOR]

The C10a‐acetoxylated tetrahydroazepino[1,2‐a]indole‐6,11‐diones are a class of tricyclic oxindoles that feature an α‐keto‐N,O‐acetal substructure, rendering them highly susceptible to SET reduction followed by fragmentation. In protic medium, they undergo a PCET‐assisted two‐step reduction including an interposed C−O bond cleavage that can be initiated photocatalytically as well as by cathodic reduction, and which generates nucleophilic ketyl radicals. In the presence of acrylonitrile and DIPEA as additional reactants, the photoinduced reaction unfolds as a tandem C−O bond reduction/ketyl radical conjugate addition, to furnish C10a‐reduced, C11‐cyanoethyl‐substituted tricyclic azepino‐[1,2‐a]indole derivatives with high stereoselectivity. [ABSTRACT FROM AUTHOR]

Mung bean sprouts are widely consumed as a seasonal fresh vegetable, renowned for their affordability and richness in antioxidants and bioactive compounds. This study employed ultra‐high‐performance liquid chromatogram‐Q‐Exactive HF mass spectrometry (UHPLC‐QE‐MS) and multivariate statistical analysis to comprehensively evaluate the chemical profile of mung bean sprouts following sulfite immersion. The findings revealed a significant alteration in the overall chemical composition of mung bean sprouts following sodium sulfite immersion. Eleven components, including four sulfur‐containing compounds, were identified as characteristic markers distinguishing between non‐immersed and sodium sulfite‐immersed mung bean sprouts. Esterification and addition reactions were inferred to occur during sodium sulfite immersion, leading to the transformation of flavonoid and saponin sulfates. Commercial samples analysis indicated that sulfur‐containing compounds were detectable in 9 of 11 commercial mung bean sprouts. Meanwhile, when sodium sulfite concentration exceeded 3.00 mg/mL and immersion time exceeded 360 min, the contents of total polyphenol and flavonoid were significantly reduced and the antioxidant activity was adversely influenced. [ABSTRACT FROM AUTHOR]

HTPB (hydroxyl‐terminated polybutadiene) is a well‐established binder in the composite solid propellant owing to its excellent compatibility with ammonium perchlorate (AP) and aluminium (Al) particles in giving rise to optimal ballistic and mechanical properties. Efforts are being made to improve the ballistic properties further, such as specific impulse. One way of increasing the specific impulse is to hydrogenate HTPB, which decreases the molecular mass of the combustion product gases. This paper is a summary of efforts in synthesizing hydrogenated HTPB (HHTPB) using copper chromite (CC) as a catalyst. A novel synthesis methodology is developed for HHTPB using a temperature‐programmed batch reactor with a variable speed stirrer and an instrumentation system to maintain the desired liquid reactant temperature. A process cycle is developed that includes addition sequence and reaction time. The product is analyzed using 1H‐NMR and FTIR to estimate the degree of hydrogenation and the geometrical isomers respectively. The estimated apparent equilibrium rate constants from the degree of hydrogenation values are respectively 74 and 2034 L/(mol MPa) for non‐catalyzed and catalyzed systems, indicating the effectiveness of the catalyst. This is also substantiated by the reduction in Gibbs free energy (ΔG), to an extent of 4.48 kJ/mol. Thermogravimetry examination indicates that the decomposition temperature of HHTPB produced by the catalytic method is marginally higher compared to HTPB. DSC curves indicate that the decomposition enthalpy of HHTPB is higher than that of HTPB. In summary, this paper proposed and validated a novel method in the preparation of HHTPB using copper chromite. [ABSTRACT FROM AUTHOR]

Bio‐inspired unidirectional flow of tiny aqueous droplets across the fibrous substrate paved the way for the emergence of various advanced materials. In the past, textiles decorated with noncontact‐based wettability‐patterns enabled unidirectional water flow—without flooding the top surface by the transferred water. However, such approaches mostly suffer from a low (≈0.176 µL mm−2 s−1) flow rate and are likely to delay the overall liquid ejection process. Here, a chemically reactive coating capable of tailoring water wettability (121.3° ± 2.4° to 153.3° ± 1.8°) is introduced on commercially available textiles to develop chemically modulated wettability‐pattern for achieving a rapid (2.57 ± 0.28 µL mm−2 s−1) flow rate of water against the gravity with an ability to roll the accumulated liquids on the top surface. The spatially selected and controlled chemical modification with hydrophilic and hydrophobic small molecules through a 1, 4‐conjugate addition reaction yielded a 3D channel with a customized wettability gradient. The pinning and depinning of invaded water through such chemically decorated channels enabled unidirectional and fast penetration of liquid, where the water penetration resistance largely depends on the water penetration direction and dimension of the chemically modulated channels. [ABSTRACT FROM AUTHOR]

Oximes, belonging to imines with the general formula of RR'C=NOH, are produced by the nucleophilic addition reaction between hydroxylamine with ketones or aldehydes, yielding corresponding aldoxime and ketoxime. The presence of hydrogen bond acceptor and donor is the classical feature of oxime‐containing structural framework. This review presents a summary of the role of oximes and its structure activity relationships including antimicrobial, anticancer, anti‐inflammatory, antihyperglycemic, insecticidal agents, along with their involvement in the treatment of organophosphorus poisoning. The review also focused on the pharmacological profile of lead molecules of several classes of oxime‐containing compounds. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Eight zwitterionic rare earth metal complexes stabilized by amino‐bridged tris(phenolato) ligands bearing quaternary ammonium side‐arms were synthesized and characterized. These complexes were used as single‐component catalysts for the cycloaddition of CO2 and epoxides, and their catalytic activities are obviously higher than those of their binary analogues. Further studies revealed that the halide anions (Cl–, Br–, I–) and the metal complexes influenced the catalytic activity, and the lanthanum complex bearing iodide anion showed the highest catalytic activity for this addition reaction. A variety of mono‐substituted epoxides were converted to cyclic carbonates in good to excellent yields (55%—99%) with high selectivity (> 99%) at 30 °C and 1 bar CO2, whereas internal epoxides required higher both reaction temperatures (60—120 °C) and catalyst loading (2 mol%) for high yields. The catalyst was recyclable for four times without noticeable loss of catalytic activity. Based on the results of kinetic studies and in situ IR reactions, a plausible reaction mechanism was proposed. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of indolo[2,1-a]isoquinolines using calcium carbide as an alkyne source, 2-(2-bromophenyl)-1H-indoles as starting materials, and copper as a catalyst is described. The target products are synthesized via Sonogashira cross-coupling/nucleophilic addition tandem reactions. The advantages of this protocol include the use of inexpensive and easy-to-handle solid alkyne source instead of flammable and explosive gaseous acetylene, cheap and readily available raw materials, wide range of substrates, and simple reaction procedure. The method can also be extended to gram scale. In addition, the desired product can also be obtained by one-pot three-component reaction of phenylhydrazine hydrochlorides, o-bromoacetophenones and calcium carbide. [ABSTRACT FROM AUTHOR]

The cluster of four skipped exo‐methylene substituents on the "northern" wing of limaol renders this dinoflagellate‐derived marine natural product unique in structural terms. This arguably non‐thermodynamic array gains kinetic stability by virtue of populating local conformations which impede isomerization to a partly or fully conjugated polyene. This analysis suggested that the difficulties encountered during the late stages of our first total synthesis of this polyketide had not been caused by an overly fragile character of this unusual substructure; rather, an unfavorable steric microenvironment about the spirotricyclic core was identified as the likely cause. To remedy the issue, the protecting groups on this central fragment were changed; in effect, this amendment allowed all strategic and practical problems to be addressed. As a result, the overall yield over the longest linear sequence was multiplied by a factor of almost five and the material throughput increased more than eighty‐fold per run. Key‐to‐success was a gold‐catalyzed spirocyclization reaction; the reasons why a Brønsted acid cocatalyst is needed and the origin of the excellent levels of selectivity were delineated. The change of the protecting groups also allowed for much improved fragment coupling processes; most notably, the sequence of a substrate‐controlled carbonyl addition reaction followed by Mitsunobu inversion that had originally been necessary to affix the southern tail to the core could be replaced by a reagent controlled asymmetric allylation. Finally, a much‐improved route to the "northern" sector was established by leveraging the power of asymmetric hydrogenation of a 2‐pyrone derivative. Limaol was found to combine appreciable antiparasitic activity with very modest cytotoxicity. [ABSTRACT FROM AUTHOR]

The development of highly efficient and stable visible-light-driven photocatalysts for the removal of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water is still a challenge. In this work, Bi2MoO6 (BMO) materials with different morphology were successfully prepared via a simple hydrothermal method by altering the solvent. The morphology of the BMO material is mainly influenced by the solvent used in the synthesis (H2O, ethanol, and ethylene glycol or their mixtures) and to a lesser extent by subsequent thermal annealing. BMO with aggregated spheres and nanoplate-like structures hydrothermally synthesized in ethylene glycol (EG) and subsequently calcined at 400 °C (BMO-400 (EG)) showed the highest adsorption capacity and photocatalytic activity compared to other synthesized morphologies. Complete degradation of 2,4-D on BMO upon irradiation with a blue light-emitting diode (LED, λmax = 467 nm) was reached within 150 min, resulting in 2,4-dichlorophenol (2,4-DCP) as the main degradation product. Holes (h+) and superoxide radicals (⋅O2−) are assumed to be the reactive species observed for the rapid conversion of 2,4-D to 2,4-DCP. The addition of H2O2 to the reaction mixture not only accelerates the degradation of 2,4-DCP but also significantly reduces the total organic carbon (TOC) content, indicating that hydroxyl radicals are crucial for the rapid mineralization of 2,4-D. Under optimal conditions, the TOC value was reduced by 84.5% within 180 min using BMO-400 (EG) and H2O2. The improved degradation performance of BMO-400 (EG) can be attributed to its particular morphology leading to lower charge transfer resistance, higher electron–hole separation, and larger specific surface area. [ABSTRACT FROM AUTHOR]

Bio‐based, fully degradable aliphatic‐aromatic block copolymers are synthesized from ω‐pentadecalatone and cyclic oligo(3,4‐ethylene furanoate). In the first approach, the ring‐opening polymerization of the cyclic oligo(3,4‐ethylene furanoate) is initiated by a poly(pentadecalactone) macroinitiator with a terminal hydroxy group. The reaction temperatures of the melt polymerization are 210–230 °C due to the high melting points of the oligo(3,4‐ethylene furanoate). Under these conditions, transesterification is observed. The blockiness of the reaction products depends on the reaction temperature and on the ratio of pentadecalactone to 3,4‐ethylene furanoate repeat units, which is 50:50, 80:20, and 90:10. At lower temperatures and more pentadecalactone content, the blockiness is larger. The number average molar mass of the block copolymers remains smaller than 20 000 g mol−1. In the second approach, poly(pentadecalactone) is functionalized with an alkyne group, and the OH group of the oligo(3,4‐ethylene furanoate) (molar mass 1900 g mol−1) is converted into an azide group. Connecting the two polymers in a copper‐catalyzed 1,3‐dipolar addition reaction ("click reaction") yields block copolymers with a number average molar mass of 12 400 g mol−1. The mechanical properties of the polymer films are intermediate between those of the parent homopolymers. [ABSTRACT FROM AUTHOR]

We describe herein the additive‐controlled divergent [4+2] cycloaddition and 1,4‐Michael addition reaction of benzofuran‐derived azadienes (BDAs) with enamides. An unprecedented [4+2] cycloaddition reaction of BDAs and enamide compounds was developed in the presence of 4 Å MS, providing a variety of structurally complex decahydrobenzofuro[3,2‐b]quinolines (13 examples) in moderate to excellent yields (59–98 % yields) with single diastereoisomer obtained. While employing MgSO4 as desiccant, the chemoselectivity was switched to the 1,4‐addition reactions, leading to a wide range of highly functionalized hybrids of benzofurans and enamide compounds (25 examples) in 25–94 % yields under mild conditions. [ABSTRACT FROM AUTHOR]

Thiophene is the organic sulfur with good thermal stability in carbon-based fuel, clarifying the conversion mechanism between thiophene and COS is beneficial for achieving in-situ sulfur fixation during CO2 gasification of carbon-based fuels, but the mechanism has rarely been reported. Therefore, calculations based on density functional theory were performed and 16 reaction paths were proposed in this research, clarifying the decomposition mechanism of thiophene and re-fixation mechanism of COS. The attachment of CO2 will lead to the destruction of the thiophene ring and the generation of COS, and CO2 adsorption is the rate-determined step, while the carbon atom that adjacent sulfur atom is the reaction active site. However, the energy barriers of CO2 addition reactions are lower than those of CO2 adsorption reactions, and the energy barrier of reactions occurring on the aliphatics are lower than that occurring on the aromatics. The combination of CO2 and thiophene will thermodynamically lead to the generation of COS and CO. Moreover, gaseous sulfur generated from thiophene decomposition will be converted mutually, while H2S will not be converted into COS. Furthermore, COS will be captured by char, forming solid organic sulfur. The re-fixation of COS will occur on aliphatic chains from the decomposition of aromatics. [ABSTRACT FROM AUTHOR]

We have developed radical C‐glycosylation using photoexcitable unprotected glycosyl borate. The direct excitation of glycosyl borate under visible light irradiation enabled the generation of anomeric radical without any photoredox catalysts. The in situ generated anomeric radical was applicable to the radical addition such as Giese‐type addition and Minisci‐type reaction to introduce alkyl and heteroaryl groups at the anomeric position. In addition, the radical–radical coupling between the glycosyl borate and acyl imidazolide provided unprotected acyl C‐glycosides. [ABSTRACT FROM AUTHOR]

Generation of lignin-carbohydrate complex (LCC) between dehydrogenation polymer (DHP) and pulp fibers may have an important impact on the properties of pulp. In this work, the benzyl ester-type LCC was formed between oxidized cellulose and DHP. The effect of pH on the addition reaction of oxidized cellulose to quinone methide in the synthesis of DHP-cellulose complex (DHPCC) was investigated. The structure of the product was characterized by Fourier Transform Infrared (FTIR), Carbon 13-Nuclear Magnetic Resonance (13C-NMR), and 2-Dimensional Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance (2D HSQC NMR) analyses. The results indicated that cellulose was indeed oxidized and carboxyl groups were introduced into cellulose by the oxidation process. The formed DHPCC was connected by benzyl ester linkage. In addition, the pH of the reaction system had an important role in the formation of the benzyl ester bonds. The acidic condition (pH = 4.0) was conducive to the addition reaction of quinone methide with carboxyl groups of cellulose. Overall, this study provides helpful guidance for the generation of LCC between DHP and paper pulp fibers. [ABSTRACT FROM AUTHOR]

In this minireview we survey the challenges and strategies in gold redox catalysis. Gold's reluctance to oxidative addition reactions due to its high redox potential limits its applicability. Initial attempts to overcome this problem focused on the use of sacrificial external oxidants in stoichiometric amounts to bring Au(I) compounds to Au(III) reactive species. Recently, innovative approaches focused on employing hemilabile ligands, which are capable of coordinating to Au(I) and stabilizing square‐planar Au(III) intermediates, thus facilitating oxidative addition steps and enabling oxidant‐free catalysis. Notable examples include the use of the (P^N) bidendate MeDalphos ligand to achieve various cross‐coupling reactions via oxidative addition Au(I)/Au(III). Importantly, hemilabile ligand‐enabled catalysis allows merging oxidative addition with π‐activation, such as oxy‐ and aminoarylation of alkenols and alkenamines using organohalides, expanding gold's versatility in C−C and C‐heteroatom bond formations and unprecedented cyclizations. Moreover, recent advancements in enantioselective catalysis using chiral hemilabile (P^N) ligands are also surveyed. Strikingly, versatile bidentate (C^N) hemilabile ligands as competitors of MeDalphos have appeared recently, by designing scaffolds where phosphine groups are substituted by N‐heterocyclic or mesoionic carbenes. Overall, these approaches highlight the evolving landscape of gold redox catalysis and its tremendous potential in a broad scope of transformations. [ABSTRACT FROM AUTHOR]

Ring-opening addition reaction between a tri-aziridine, pentaerythriyol-tris[3-(1-aziridinyl)propionate] (AZOH) or 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] (AZ), and a thiol-carboxylic acid, thioglycolic acid (TGA) or thiolactic acid (TLA) or 3-mercaptopropionic acid (MPA), at room temperature in ethyl acetate produced porous polymers. The polymer networks were formed by the ring-opening reactions between the aziridine group of the tri-aziridine compounds with both the carboxylic acid and thiol groups of the thiol-carboxylic acids. The morphology of the porous polymers was composed by connected particles, whose averaged diameters ranged from about 2.5 to 7.5 µm. The reaction of AZOH and MPA under a high monomer concentration (40 wt%) yielded the porous polymer with co-continuous monolithic structure, whose backbone was formed by connected small particles of diameters of less than 0.2 µm. The porous polymers formed with TLA showed higher Young's modulus due to small particle size and high density. The porous polymers showed good thermal stability. All porous polymers were decomposed in methanol within 50 days at room temperature. [ABSTRACT FROM AUTHOR]

A possibility of use of the Michael addition reaction of the A, Bring fragment enolate to sulfoxide 2(S)[(4methyl phenyl) sulfinyl]2cyclopenten1one for constructing the main skeleton of 9,11secosterols was studied. The reaction was conducted with the racemic or the enantiomerically enriched sulfoxide as the acceptor, affording a mixture of five or three main diastereomers, respectively. It was shown that the diastereoselectivity of that addition reaction is relatively low and does not afford a competitive new route for the total synthesis of secosterols. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) is a greenhouse gas, and its resource use is vital for carbon reduction and neutrality. Herein, the nucleophilic addition reaction of calcium carbide (CaC2) to CO2 was studied for the first time to synthesize propiolic and butynedioic acids by using CuI or AgNO3 as catalyst, Na2CO3 as additive, and triphenylphosphine as ligand in the presence/absence of a hydrogen donor. The effects of the experimental conditions and intensification approach on the reaction were investigated. The reactivity of CaC2 is closely associated with its synergistic activation by the catalysts, solvent, and external intensification, such as the ultrasound and mechanical force. Ultrasound helps to promote the reaction by enhancing the interfacial mass transfer of CaC2 particulates. Mechanochemistry can effectively promote the reaction, yielding 29.8% of butynedioic acid and 74.8% of propiolic acid after 2 h ball milling at 150 rpm, arising from the effective micronization and interfacial renewal of calcium carbide. The present study sheds a light on the high-value uses of CO2 and CaC2 and is of reference significance for the nucleophilic reaction of CaC2 with other carbonyl compounds. [ABSTRACT FROM AUTHOR]

Light curing 3D printing technology has become an emerging technology in the manufacturing industry because of its high precision, rapid prototyping, and complex parts can be formed. Photosensitive resin is the main consumable of light curing 3D printing technology, and its mechanical properties, heat resistance, precision and strength are not ideal enough to meet the needs of industrial production. In order to obtain the photosensitive resin with high mechanical strength and function, it must be modified. In this paper, the modification of photosensitive resin for photocuring 3D printing is introduced. Starting with the principle of SLA photocuring rapid prototyping technology, the various components of photosensitive resin are introduced, and the modification of photosensitive resin is shown from the two aspects of reaction type and addition type. Finally, the development trend of photosensitive resin is prospected. It is pointed out that in the future, on the basis of perfecting the existing photosensitive resin materials, more new materials for 3D printing will be developed, resin formula will be expanded, and more in-depth research will be carried out on the modification of photosensitive resins, so as to develop more high-performance, higher-strength, and greener resin systems. [ABSTRACT FROM AUTHOR]

Developing effective latent curing agent for rapid curing of epoxy resins at low temperatures remains challenging. This study reports a latent curing agent, ortho‐cresol phenolic epoxy resin‐bisphenol A (EOCN‐BPA), prepared through the addition reaction of o‐methyl phenolic epoxy resin with BPA. When blended with dicyandiamide (DICY) in a 1:3 molar ratio, EOCN‐BPA/DICY is used to cure a linear epoxy phenolic novolac (EPN) resin (epoxy equivalent: 550 g eq−1, softening point: approximately 82°C), at an onset curing temperature of 90°C, which is considerably lower than the onset curing temperature of DICY with EPN (160°C). However, EOCN‐BPA does not react with EPN without a catalyst. Therefore, this latent curing system is successfully applied in powder coatings, rapid curing at 120°C within 3 min without an additional catalyst, outperforming the EPN/EOCN‐BPA system using cocatalyst 2‐methylimidazole. Consequently, DICY catalyzes the curing reaction between the phenol hydroxyl group and epoxy resin and participates in it. The prepared powder coating exhibits excellent storage stability, maintaining its properties for over 3 months at room temperature. These findings demonstrate the excellent latent properties of EOCN‐BPA/DICY, highlighting its potential as a highly effective latent curing agent. [ABSTRACT FROM AUTHOR]

Polymers consisting of more than one type of monomer, known as copolymers, are vital to both living and synthetic systems. Copolymerization has been studied theoretically in a number of contexts, often by considering a Markov process in which monomers are added or removed from the growing tip of a long copolymer. To date, the analysis of the most general models of this class has necessitated simulation. We present a general method for analyzing such processes without resorting to simulation. Our method can be applied to models with an arbitrary network of sub-steps prior to addition or removal of a monomer, including non-equilibrium kinetic proofreading cycles. Moreover, the approach allows for a dependency of addition and removal reactions on the neighboring site in the copolymer and thermodynamically self-consistent models in which all steps are assumed to be microscopically reversible. Using our approach, thermodynamic quantities such as chemical work; kinetic quantities such as time taken to grow; and statistical quantities such as the distribution of monomer types in the growing copolymer can be directly derived either analytically or numerically from the model definition. [ABSTRACT FROM AUTHOR]

The hydrochlorination of alkenes has been extensively studied in research and is commonly featured in organic chemistry textbooks as an exemplification of the Markovnikov rule. However, the application of this reaction is typically limited to specific alkenes, such as highly substituted ones, styrenes, or strained systems. Conversely, monosubstituted or 1,2-disubstituted alkenes do not readily react with HCl gas or solutions of HCl gas at practical rates. The challenges associated with hydrochlorination reactions for these "non-activated" alkenes have spurred considerable research efforts over the past 30 years, which constitute the primary focus of this review. The discussion begins with classical polar hydrochlorinations, followed by metal-promoted radical hydrochlorinations, and concludes with a brief overview of recent anti-Markovnikov hydrochlorinations.

Acetic acid reforming is a green method for sustainable hydrogen production owing to its renewable source from biomass conversion. However, conventional acetic acid reforming would produce various byproducts, including CO, CH4 and so on. Here, we develop a distinctive method for selective hydrogen production from C--C directional cleavage during acetic acid reforming. Completely different from conventional acetic acid reforming process, acetic acid would react with water over organoruthenium catalyst during its C--C cleavage at low temperature, then produce methanol and formic acid (CH3COOH+H2O→CH3OH+HCOOH). Lastly, methanol and formic acid could further decompose into hydrogen and carbon dioxide over organoruthenium selectively. As a result, there is little CO and CH4 produced in the first step of C--C bond cleavage during acetic acid reforming at 100 °C. Hydrogen production rate is up to 26.8 molH2/(h-1*mol-1Ru) at 150°C through a tandem catalysis. A mechanism for C--C cleavage of acetic acid is proposed based on intermediate product analysis and density functional theory (DFT) calculation. Firstly, the C--C single bond was transformed into C=C double bond by dropping one H atom to organoruthenium. Then the coming H2O molecule reacted with the C=C bond by an addition reaction, forming methanol and formic acid. This research not only proposes distinctive reaction pathway for hydrogen production from acetic acid reforming, but also provides some inspiration for selective C--C bond cleavage during ethanol reforming. [ABSTRACT FROM AUTHOR]

β‐Tertiary amino acid derivatives constitute one of the most frequently occurring units in natural products and bioactive molecules. However, the efficient asymmetric synthesis of this motif still remains a significant challenge. Herein, we disclose a cobalt‐catalyzed enantioselective reductive addition reaction of ketimine using α‐chloro carbonyl compound as a radical precursor, providing expedient access to a diverse array of enantioenriched β‐quaternary amino acid analogues. This protocol exhibits outstanding enantioselectivity and broad substrate scope with excellent functional group tolerance. Preliminary mechanism studies rule out the possibility of Reformatsky‐type addition and confirm the involvement of radical species in stereoselective addition process. The synthetic utility has been demonstrated through the rapid assembly of iterative amino acid units and oligopeptide, showcasing its versatile platform for late‐stage modification of drug candidates. [ABSTRACT FROM AUTHOR]

Using thiol–ene chemistry, polymerization-induced phase separation, and DLP 3D printing, we present a method for manufacturing reactive macroporous 3D structures. This approach enables the fabrication of structures with tunable physicochemical properties and compressibility. Moreover, it facilitates post-functionalization through thiol-Michael addition reactions, thereby expanding performance and application potential. [ABSTRACT FROM AUTHOR]

This article explores the use of dihydroaromatic compounds as hydrogen donors in transfer hydrogenation reactions. The authors investigate the effectiveness of different Lewis acid catalysts, including silicon-, boron-, and indium-based catalysts, as well as Fe, Co, and Ni halides. They also examine the use of chiral hydride sources for asymmetric transfer hydrogenation. The study finds that FeBr3 is a highly reactive and cost-effective catalyst for transfer hydrogenation reactions, producing moderate to excellent yields of desired products. The catalyst is effective for a range of alkenes, including tetrasubstituted alkenes. Mechanistic studies are conducted to understand the reaction pathway. [Extracted from the article]

Acyclic diaminocarbenes (ADCs)–Metal complex having strong donor ability and thermal stability led to extensive usability across every area of inorganic and organometallic chemistry. The unique properties of acyclic diaminocarbenes (ADCs) provide certain advantages over other carbene ligands and have the potential to make a great impact in catalysis. Further, the straightforward synthesis of M–ADCs (metal bound acyclic diaminocarbenes) complexes via metal-mediated reaction provides a wide range of well-defined metal carbene catalysts, which might inspire more researchers to devise unsymmetrically substituted, chiral, and novel acyclic carbene compounds. Although the above synthetic route is limited to a few late transition metals, but have great opportunities to expand the scope of this method. The application of M–ADCs complexes as a catalyst for several organic transformation reactions such as various cross-coupling reactions and asymmetric synthesis like hydroarylation, hydroazidation, hydroamination, cyclization and addition reactions which have shown comparable or even higher activities than the analogous M–NHCs based on all the reports presented. Recent findings of donor ability of several ADC ligands would be useful in fine-tuning the electronic properties, and then a catalyst with a certain combination of donicity and steric requirement could open new doors in catalytic reactivity. Thus, the objective of this review is to assess the recent growths that have been made in designing novel and chiral ADCs ligands and synthesizing ADCs–Metal complexes and to highlight catalytic activities of metal acyclic diaminocarbene complexes for cross-coupling reactions. [ABSTRACT FROM AUTHOR]

Chiral mono- and bis-(thio)urea supramolecular organocatalysts were studied in the enantioselective vinylogous addition reaction of 2-trimethylsilyloxyfuran (TMSOF) to carbonylic compounds; the corresponding chiral γ-hydroxymethyl-butenolides are obtained in good yields and with high enantiomeric excesses. The catalyst structure, as well as the reaction conditions, strongly influence the efficiency of the reaction. The conformational features of mono(thio)urea catalysts 2 and 3 and bis(thio)urea catalysts 7 and 8 were investigated by DFT calculations along with the structure of their complexes with benzaldehyde. Natural Bond Orbital (NBO) and Non-Covalent Interaction (NCI) calculations provided useful information concerning the activating H-bonding interactions in the complexes. [ABSTRACT FROM AUTHOR]

This study investigated the effects of Ga doping (0.1–1 wt.% Ga) on Sn-Ga/Cu interfacial reactions. In liquid-state reactions at 250°C, the addition of 0.1 wt.% and 0.2 wt.% Ga induced the formation of scallop-shaped Cu6Sn5 and Cu3Sn phases, with ripening of Cu6Sn5 grains. However, Ga concentrations > 0.5 wt.% led to an unstable microstructure evolution. Initially, a thin layer of γ1-Cu9Ga4 formed but later detached and disintegrated in the solder, followed by Cu6Sn5 formation. Notably, Ga enhanced Cu6Sn5 nucleation, refining grains and promoting faster growth. The solid-state Sn-Ga/Cu reactions were also examined at 140°C to 200°C. Adding 0.2 wt.% Ga had no significant influence on the Cu6Sn5 and Cu3Sn formation, but the Cu3Sn/Cu6Sn5 thickness ratio increased with decreasing aging temperature, probably because of the higher Cu diffusion to Sn at lower temperatures. However, the interface with 0.5 wt.% Ga became unstable, particularly < 160°C, resulting in Cu6Sn5 dissolution, phase fracture, and Cu substrate dissolution. This instability was attributed to Cu outer-diffusion induced by Ga at lower temperatures. In contrast, the interface was relatively stable at 200°C. Similar interfacial results were observed with 1 wt.% Ga. Additionally, the phase equilibria of Sn-Ga-Cu system at 250°C were investigated to discuss the interfacial reactions. [ABSTRACT FROM AUTHOR]

The reactivity of 22 unsaturated molecules undergoing attack by a methyl radical (⋅CH3) have been elucidated using the condensed radical general‐purpose reactivity indicator (condensed radical GPRI) appropriate for relatively nucleophilic or electrophilic molecules. Using the appropriate radical GPRI equation for electrophilic attack or nucleophilic radical attack, seven different population schemes were used to assign the most reactive atoms in each of the 22 molecules. The results show that the condensed radical GPRI is sensitive to the population scheme chosen, but less sensitive than the radical Fukui function. Therefore, the reliability of these methods depends on the population scheme. Our investigation indicates that the condensed radical GPRI is most accurate in predicting the dominant products of the methyl radical addition reactions on a variety of unsaturated molecules when the Hirshfeld, Merz–Singh–Kollman, or Voronoi deformation density population schemes are used. Furthermore, for all populations schemes in the majority of instances where the radical Fukui function failed the radical GPRI was able to identify the most reactive atom under certain reactivity conditions. [ABSTRACT FROM AUTHOR]

Despite the significance of chiral allene skeletons in catalysis, organic synthesis and medicinal chemistry et al. there is a scarcity of reports on axially chiral allenyl phosphorus compounds. Here, we disclosed an efficient and straightforward cascade reaction between ethynyl ketones and phosphine oxides, resulting in a broad array of trisubstituted allenes incorporating a phosphorus moiety in high yields with excellent stereoselectivities facilitated by peptide‐mimic phosphonium salt (PPS) catalysis, Additionally, comprehensive series of mechanistic experiments have been conducted to elucidate that this cascade reaction proceeds via an asymmetric Pudovik addition reaction followed by a subsequent phospha‐Brook rearrangement that occurs concomitantly with kinetic resolution, representing a stereospecific rearrangement and protonation process facilitating central‐to‐axial chirality transfer in a cascade manner. We anticipate that our research will pave the way for a promising exploration of novel stereo‐induction pattern in the Pudovik addition/phospha‐Brook rearrangement cascade reaction. [ABSTRACT FROM AUTHOR]

We investigated the inhibition of thermal runaway of styrene polymerization by DNPB. DNBP is an inhibitor in styrene polymerization reaction. Polymerization is one of eighteen hazardous processes. Styrene polymerization reaction is characterized by high heat production and fast reaction rate. Firstly, differential scanning calorimetry (DSC) and adiabatic calorimetry (ARC) were chosen to study the effect of different mass of DNBP on thermal behavior in non-isothermal and adiabatic environments. Secondly, exploring the inhibitory effect of DNBP at different runaway temperatures using an oil bath reactor. The results showed that when DNBP was at 0.80%, effective inhibition was obtained at different runaway temperatures. Finally, GC/MS and Gauss16 were used to infer the mechanism of inhibition in terms of macroscopic products and microscopic instabilities. The results showed that the products of the oil bath reactor experiments were related to the mass of DNBP, and when DNBP was 0.80%, the products increased and the main reaction was inhibited. Finally, it was deduced that the nitro group undergoes a possible path of direct addition reaction with the styrene radical before bond breaking. [ABSTRACT FROM AUTHOR]

Quinones are valuable structural motifs found in numerous natural products and pharmaceuticals. In particular, p-benzoquinones are of great interest because of their ready availability and versatile reactivity. They can serve as good Michael acceptors and participate in many cycloaddition, nucleophilic addition and multicomponent reactions. However, the construction of polycyclic architectures with increased stereochemical features is another perspective of quinone chemistry. The present review summarizes the recent advances (2018–2023) in stereoselective annulation involving p-benzoquinones for the construction of fused, spiro and bridged/cage frameworks. In this regard, different types of annulations, such as [3+2], [3+3], [3+2+1], [4+2] and [2+2], are discussed for accessing diverse fused heterocycles in a stereoselective manner. Some novel annulation methods are reviewed for building spiro heterocycles and cage molecules. Most of the reactions described in this review are simple, providing quick formation of the desired products with high stereoselectivity. In this regard, typical reaction mechanisms are presented to understand how quinoidal scaffolds show variable reactivity towards reaction partners. [ABSTRACT FROM AUTHOR]