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Vicinal stereogenic centers represent prevalent structural motifs in organic synthetic chemistry, and their construction poses a longstanding challenge. Transition-metal-catalyzed asymmetric allylic substitution has become a well-established enantioselective C–C bond-forming reaction. When these reactions involve a prochiral nucleophile and an allylic electrophile with a terminal substituent, the creation of vicinal stereogenic centers becomes feasible. However, despite remarkable achievements having been accomplished, realizing this transformation with precise control over both the enantio- and diastereoselectivity remains a significant challenge. To address the stereoselective challenges, the introduction of a second catalyst to the transition-metal-catalyzed asymmetric allylic alkylation to control the diastereoselectivity during C–C bond formation has proven particularly fruitful. In this short review, we aim to highlight recent advances in dual catalysis that enable diastereo- and enantioselective allylic substitutions. 1 Introduction 2 Construction of Vicinal Stereogenic Centers by Organo and Metal Dual Catalysis 2.1 Chiral Phase-Transfer Catalysis and Transition-Metal Dual Catalysis 2.2 Chiral Amine and Transition-Metal Dual Catalysis 2.3 NHC and Transition-Metal Dual Catalysis 2.4 Chiral Aldehyde and Transition-Metal Dual Catalysis 2.5 Chiral Lewis Base and Transition-Metal Dual Catalysis 3 Construction of Vicinal Stereogenic Centers by Metal and Metal Dual Catalysis 3.1 Lewis Acidic Metal and Iridium Dual Catalysis 3.2 Lewis Acidic Metal and Palladium Dual Catalysis 3.3 Palladium and Ruthenium Dual Catalysis 3.4 Other Advancements in the Construction of Vicinal Stereogenic Centers through Synergistic Bimetallic Catalysis Enabling Asymmetric Allylic Alkylation 4 Conclusions and Future Outlook [ABSTRACT FROM AUTHOR]

In this paper, an exceptional nitrate reduction to ammonia catalyst is reported, enabled by BO2− anion induction effects combining heterogeneous branching architecture‐driven mass transport enhancement strategies. The implantation of the BO2− anion can inductively enhance the electron cloud density and electron transmission paths of intrinsic catalysts, makes electron more active to improve the conductivity, regulates the adsorption and desorption rates of intermediates by space barrier effect, reduces the binding energy of the electron and 3d orbital of Ni in NiFe(BO2)O(OH), thereby lowing the transform free energy of the determining *NO3 to *HNO3 step. 3D hollow sea urchin lattice heterogeneous branching structure can self‐drive generate differentiated micro convection intervals, which will be beneficial for improving mass transfer dynamics especially localized disturbance mass transfer effect of catalyst for nitrate reduction reaction (NO3RR) catalysis process. Amazingly, the as‐prepared 3D NiFe metaborate oxyhydroxide hollow bionic sea urchins lattice catalyst has a high NH3 rate 6.27mmol·h−1·cm−2 with 98.7% Faradaic efficiency at low ‐0.25V(vs RHE) NO3RR potential. Moreover, the catalytic activity of this highly stable catalyst decreases only slightly over 100 h at ultra‐high 1500mA·cm−2 current. This work breaks through the bottleneck that plagues the performance improvement of non Cu‐based high‐current NO3RR catalysts. [ABSTRACT FROM AUTHOR]

A general phase‐transfer catalyst (PTC) mediated enantioselective alkylation of N‐acylsulfenamides is reported. Essential to achieving high selectivity was the use of the triethylacetyl sulfenamide protecting group along with aqueous KOH as the base under biphasic aqueous conditions to enable the reaction to be performed at −40 °C. With these key parameters, enantiomeric ratios up to 97.5 : 2.5 at the newly generated chiral sulfur center were achieved with an inexpensive cinchona alkaloid derived PTC. Broad scope and excellent functional group compatibility was observed for a variety of S‐(hetero)aryl and branched and unbranched S‐alkyl sulfenamides. Moreover, to achieve high selectivity for the opposite enantiomer, a pseudoenantiomeric catalyst was designed and synthesized from inexpensive cinchonidine. Given that sulfoximines are a bioactive pharmacophore of ever‐increasing interest, selected product sulfilimines were oxidized to the corresponding sulfoximines with subsequent reductive cleavage affording the free‐NH sulfoximines in high yields. The utility of the disclosed method was further demonstrated by the efficient asymmetric synthesis of atuveciclib, a phase I clinical candidate for which only chiral HPLC separation had previously been reported for isolation of the desired (R)‐sulfoximine stereoisomer. [ABSTRACT FROM AUTHOR]

The synthesis of asymmetric organic molecules has experienced a huge development over the last few decades. Phase‐transfer catalysis has been proven to be one of the most powerful methods for these asymmetric transformations. However, the study of the mechanism of these catalysts and the different interactions that they can establish with the reactants has failed to keep pace. In the present study, the conjugate cyanation of two different α,β‐unsaturated ketones are studied in the presence of a well‐known alkaloid quinine‐derived PTC, along with different modifications. The study includes the comparison of different binding modes between the catalysts and the different reactants, the mechanistic study of the reaction and the analysis of the non‐covalent interactions established within the complexes and their role in the global enantioselectivity of the process. [ABSTRACT FROM AUTHOR]

A simple and commercially feasible route of synthesis of thiols and thioethers was developed using a simple phase transfer catalyst, i.e., Tetra Butyl Ammonium Bromide (TBAB). Sodium hydrogen sulfide (NaSH) is used as a sulfurization agent which is easily available and cost-effective. Thiols are obtained by treating alkyl or benzyl halides with sodium hydrogen sulfide (NaSH) in the presence of a phase transfer catalyst (TBAB) at 10 to 15℃. Thioethers are obtained by benzyl thiols treated with corresponding benzyl halides in the presence of a phase transfer catalyst (TBAB) at 10 to 15℃. Synthesis of thiols and thioethers is achieved by substitution reaction of benzyl or alkyl halides with sulfide in the presence of phase transfer catalyst (TBAB) and monochlorobenzene as a solvent at 10 to 15℃. Milder reaction conditions, excellent yield, shorter reaction time and operational simplicity are the key features of this procedure. [ABSTRACT FROM AUTHOR]

An eco-friendly, metal-free approach for synthesizing dihydrobenzo[b][1,8]naphthyridine derivatives has been established. This method employs ortho-chloroquinolin-α,β-unsaturated ketones as dipolarophiles and acyclic enaminones as amphiphilic nucleophiles, enabling a formal [3 + 3] annulation reaction under phase-transfer catalysis to offed the targeted products. It boasts transition-metal-free conditions, broad functional group compatibility, and straightforward operational procedures. [ABSTRACT FROM AUTHOR]

Alkylation of aromatic carbamates with allyl bromide under liquid-liquid phase transfer catalysis furnished the corresponding N-allyl derivatives of aryl carbamates in 63–71% yields. It was found that the cycloaddition of arene carbonitrile N-oxides, generated in situ from the corresponding oximes in the presence of chloramine T, to the allyl fragment upon boiling in ethanol led to the production of the corresponding 4,5-dihydroisoxazole derivatives in 89–96% yields. [ABSTRACT FROM AUTHOR]

In the presence of biphasic medium, ethyl methacrylate has been polymerized using phase transfer catalyst under silent/ultrasonic condition (53 KHz, 100 W) at 60°C (±1°C) as well as under inert atmosphere. A series of quaternary ammonium salts namely 1,4-Bis(dimethylhexyl)ethylenediammonium bromide (DMHEDAB), 1,4-Bis(dimethylheptyl) ethylenediammonium bromide (DMH1EDAB) and 1,4-Bis(dimethyloctyl) ethylenediammonium bromide (DMOEDAB) have been selected as phase transfer catalysts (PTCs). Rate of polymerization is assessed in silent and sonolytic conditions by varying the concentrations of monomer, initiator, PTCs, solvents, and temperature. The synergism of sonolysis and phase transfer catalysts increased the rate when compared to silent polymerization. Based on the results, thermodynamic values are measured, and the order of efficacy of all three catalysts are observed as DMOEDAB > DMH1EDAB > DMHEDAB. [ABSTRACT FROM AUTHOR]

This review describes the advances of heterogenous phase‐transfer catalysts onium‐based and their importance from a sustainable point of view. Although heterogeneous phase‐transfer catalysts have shown incredible advantages in many organic reactions, examples of supported phase‐transfer catalysts onium‐based are still limited. In this review, we will examine the most common supports, including polymers, clays, and inorganic materials. Additionally, new recent developments in carbon materials application as efficient heterogeneous phase‐transfer catalysts in water will be reported, opening a new route toward green and sustainable procedures. Furthermore, considering the ever‐growing interest in asymmetric synthesis we wish to discuss the important achievements in the field of chiral heterogeneous phase‐transfer catalysts. [ABSTRACT FROM AUTHOR]

[FeFe]-hydrogenases catalyze the reversible oxidation of H2 from electrons and protons at an organometallic active site cofactor named the H-cluster. In addition to the H-cluster, most [FeFe]-hydrogenases possess accessory FeS cluster (F-cluster) relays that function in mediating electron transfer with catalysis. There is significant variation in the structural properties of F-cluster relays among the [FeFe]-hydrogenases; however, it is unknown how this variation relates to the electronic and thermodynamic properties, and thus the electron transfer properties, of enzymes. Clostridium pasteurianum [FeFe]-hydrogenase II (CpII) exhibits a large catalytic bias for H2 oxidation (compared to H2 production), making it a notable system for examining if F-cluster properties contribute to the overall function and efficiency of the enzyme. By applying a combination of multifrequency and potentiometric electron paramagnetic resonance, we resolved two electron paramagnetic resonance signals with distinct power- and temperature-dependent properties at g = 2.058 1.931 1.891 (F2.058) and g = 2.061 1.920 1.887 (F2.061), with assigned midpoint potentials of −140 ± 18 mV and −406 ± 12 mV versus normal hydrogen electrode, respectively. Spectral analysis revealed features consistent with spin-spin coupling between the two [4Fe-4S] F-clusters, and possible functional models are discussed that account for the contribution of coupling to the electron transfer landscape. The results signify the interplay of electronic coupling and free energy properties and parameters of the FeS clusters to the electron transfer mechanism through the relay and provide new insight as to how relays functionally complement the catalytic directionality of active sites to achieve highly efficient catalysis. [ABSTRACT FROM AUTHOR]

Condensation of chloromethyl chlorosulfate (1) with alkyl 1,3‐keto esters under phase‐transfer catalysis (PTC) conditions led to methylene bridged bis‐acetoacetates through a sequential chloromethylation‐β‐elimination‐Michael addition process. The latter compounds further evolved towards polyfunctional dihydrofuran and tetrahydropyran derivatives by competitive chloromethylation/chlorination reaction. In aprotic organic solvent, chlorination of the methylene active group is the main process and proceeded by reaction of the enolate of acetoacetate with the chlorine atom bound to the sulfonyl group of 1. The reactivity of some other active methylene compounds under PTC conditions was investigated. Acetylacetone reacted similarly to ethyl acetoacetate providing O‐heterocycles while ethyl cyanoacetate gave diethyl 2,4‐dicyanoglutaric acid diethyl ester together with 2‐diethyl 1,2‐dicyanocyclopropane‐1,2‐dicarboxylate. A plausible reaction mechanism is proposed whose the key feature is the competitive halogenation/chloromethylation of the intermediate methylene bridge dimeric active methylene compounds followed by intramolecular cyclization. [ABSTRACT FROM AUTHOR]

It is often said that pnictogen‐bonding catalysis, and σ‐hole catalysis in general, would not work in aqueous systems because the solvent would interfere as an overcompetitive pnictogen‐bond acceptor. In this study, we show that the transfer of pnictogen‐bonding catalysis from hydrophobic solvents to aqueous systems is possible by replacing only hydrophobic with hydrophilic substrates, without changing catalyst or reaction. This differs from conventional covalent Lewis acid catalysts, which are instantaneously destroyed by ligand exchange. With their water‐proof substituents in place of exchangeable ligands, pnictogen‐bonding catalysts, the supramolecular counterpart of Lewis acid catalysts, are evinced to catalyze transfer hydrogenation of quinolines in neutral aqueous systems. To secure these results, we introduce a water‐soluble fluorogenic substrate that releases a coumarin upon the reduction of quinolines instead of activated quinolidiniums, and stiborane catalysts with deepened σ holes. They demonstrate that pnictogen‐bonding catalysts can operate in higher‐order architectures for supramolecular systems catalysis under biologically relevant conditions, and provide an operational assay for high‐throughput catalyst screening by fluorescence imaging, in situ under relevant aqueous conditions. [ABSTRACT FROM AUTHOR]

A biphasic anodic oxidation method for aromatic halogenation process was developed, where aqueous metal salts were directly used as halogen source. Ammonium salts serve as both electrolytes and phase transfer catalysis to facilitate anion transport and oxidative transformation. This design allows for chlorination or nitration of multiple types of arenes using NaCl or KNO2. [ABSTRACT FROM AUTHOR]

A method for the asymmetric synthesis of phthalides containing a stereogenic γ‐carbon has been described. The protocol, based on the arylogous Michael addition to chiral alkenoyl oxazolidinones catalyzed by a crown ether under phase‐transfer conditions does not require anhydrous conditions and uses commercially available materials. A complete syn‐stereocontrol is achieved and facial diastereoselectivities are moderate to excellent (62:38 to 99:1 dr). Purification of the major diastereomer by chromatography and selective cleavage of the chiral auxiliary affords enantiopure Michael products. The protocol has been applied to the formal synthesis of escitalopram. [ABSTRACT FROM AUTHOR]

Enantiomerically enriched crown ethers (CE) exhibit strong asymmetric induction in phase transfer catalysis, supramolecular catalysis and molecular recognition processes. Traditional methods have often been used to access these valuable compounds, which limit their diversity and consequently their applicability. Herein, a practical catalytic method is described for the gram scale synthesis of a class of chiral CEs (aza‐crown ethers; ACEs) using Rh‐catalyzed hydroamination of bis(allenes) with diamines. Using this approach, a wide range of chiral vinyl functionalized CEs with ring sizes ranging from 12 to 36 have been successfully prepared in high yields of up to 92 %, dr of up to >20 : 1 and er of up to >99 : 1. These vinyl substituted CEs allow for further diversification giving facile access to various CE derivatives as well as to their three‐dimensional analogues using ring‐closing metathesis. Some of these chiral CEs themselves display high potential for use in asymmetric catalysis. [ABSTRACT FROM AUTHOR]

A three‐component phase‐transfer catalytic domino reaction involving cyclohexane‐1,3‐dione‐derived enaminones, 5‐alkenyl rhodanines, and haloalkanes has been developed. This protocol produces a wide range of 3‐thioquinoline‐2,5‐diones in yields of 52–81%. The construction of a C−S bond at the C‐3 position of the quinoline‐2,5‐dione framework expands its structural diversity. Studies into the reaction mechanism revealed that the reaction undergoes a conjugate addition, ammonolysis, elimination, and nucleophilic substitution sequence. The synthetic potential of the reaction was demonstrated by the gram‐scale syntheses of representative products. Chloroalkyl chains were installed on the sulfur atoms of most products obtained in this reaction. Diversified product derivatives were obtained by exploiting the favorable leaving nature of the chloride moiety. [ABSTRACT FROM AUTHOR]

This document contains profiles of researchers in the field of chemistry who have made significant contributions to their respective fields. The profiles provide information about their educational background, research interests, and notable achievements. The researchers come from diverse backgrounds and work on various topics, such as organic synthesis, bio-inspired coatings, nanomaterials, and electrocatalysis. [Extracted from the article]

This research work reports the preparation of Ribociclib based on the green chemical principles such as third principle (less hazardous chemical synthesis), fifth principle (Safer solvents) and ninth principle catalysis of green chemistry that were planned and executed. Harmful solvent (chlorinated solvents)-free methodologies were executed. Highly abundant and ecofriendly Fe metal was employed for the reduction of –NO2 group to the corresponding –NH2. Phase transfer catalytic reactions were optimized twice in the coupling reactions by using simple carbonates in the preparation of side chain building and thereafter its coupling with Ribociclib precursor. A potential method for industrial practice has been executed here which is both eco- and economically friendly. [ABSTRACT FROM AUTHOR]

Benzodifurazan reacts with 1,3-dibromo-5,5-dimethylhydantoin in sulfuric acid to form 5-bromo-4,5-dihydrobenzo[1,2-c:3,4-c']bis([1,2,5]oxadiazol)-4-ol (A). The structure of the product was established by X-ray diffraction analysis. It was found that compound A exhibits properties of epoxides: it readily takes up nucleophiles to form alcohols, whose reaction with p-toluenesulfonyl chloride in the presence of tetrabutylammonium bromide and sodium hydroxide in benzene gives functional derivatives of benzodifurazan. On treatment with a base [Ca(OH)2], compound A converts to 1a,7b-dihydrooxireno[2',3':5,6]benzo[1,2-c:3,4-c']bis([1,2,5]oxadiazole). [ABSTRACT FROM AUTHOR]

A domino SNAr‐ihDA/rDA reaction was developed from rarely exploited 3‐fluoro‐1,2,4‐triazines with bifunctional alkyne tethered nucleophiles to construct various fused non‐aromatic/heteroaromatic bicycles in yields ranging from 56 to 99%, notably within the family of valuable spirooxindole derivatives. In this study, the challenging enantioselective phase‐transfer catalyzed arylation of a sulfonyl‐triazine was also demonstrated with up to 66% ee. In both racemic and asymmetric processes, the nature of the leaving group at C3 was key to successfully achieve these sequences. [ABSTRACT FROM AUTHOR]

Ion-pairing is a fundamental phenomenon that significantly influences phase-transfer catalysis. In this study, we conduct a comprehensive investigation of ion-pair interactions, aiming to establish a comprehensive understanding of their nature and implications. The study begins with the examination of polar ionic compounds to define the concept of an ion-pair in the context of phase-transfer catalysis. Subsequently, a diverse range of ion-pair catalyst models were explored to gain insight into the factors governing their interactions. Finally, the focus shifts towards the characterisation of real phase-transfer catalysts, bridging the gap between theoretical models and practical applications. Through a combination of computational approaches and theoretical analysis, this work provides valuable insight into the nature of ion-pair interactions within phase-transfer catalysis fields. [ABSTRACT FROM AUTHOR]

In recent years, metal complexes of pyridyl‐mesoionic carbene (MIC) ligands have been reported as excellent homogeneous and molecular electrocatalysts. In combination with group 9 metals, such ligands form highly active catalysts for hydrogenation/transfer hydrogenation/hydrosilylation catalysis and electrocatalysts for dihydrogen production. Despite such progress, very little is known about the structural/electrochemical/spectroscopic properties of crucial intermediates for such catalytic reactions with these ligands: solvato complexes, reduced complexes and hydridic species. We present here a comprehensive study involving the isolation, crystallographic characterization, electrochemical/spectroelectrochemical/theoretical investigations, and in‐situ reactivity studies of all the aforementioned crucial intermediates involving Cp*Rh and pyridyl‐MIC ligands. A detailed mechanistic study of the precatalytic activation of [RhCp*] complexes with pyridyl‐MIC ligands is presented. Intriguingly, amphiphilicity of the [RhCp*]‐hydride complexes was observed, displaying the substrate dependent transfer of H+, H or H−. To the best of our knowledge, this study is the first of its kind targeting intermediates and reactive species involving metal complexes of pyridyl‐MIC ligands and investigating the interconversion amongst them. [ABSTRACT FROM AUTHOR]

Rapid mass transfer in solid-solid reactions is crucial for catalysis. Although phoretic nanoparticles offer potential for increased collision efficiency between solids, their implementation is hindered by limited interaction ranges. Here, we present a self-driven long-range electrophoresis of organic nanocrystals facilitated by a rationally designed photogenerated outer electric field (OEF) on their surface. Employing perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) molecular nanocrystals as a model, we demonstrate that a directional OEF with an intensity of 13.6-0.4 kV m−1 across a range of 25–200 μm. This OEF-driven targeted electrophoresis of PTCDA nanocrystals onto the microplastic surface enhances the activity for subsequent decomposition of microplastics (196.8 mg h−1) into CO2 by solid-solid catalysis. As supported by operando characterizations and theoretical calculations, the OEF surrounds PTCDA nanocrystals initially, directing from the electron-rich (0 1 1) to the hole-rich (11 2 ¯) surface. Upon surface charge modulation, the direction of OEF changes toward the solid substrate. The OEF-driven electrophoretic effect in organic nanocrystals with anisotropic charge enrichment characteristics indicates potential advancements in realizing effective solid-solid photocatalysis. Charge accumulation in organic photocatalysts leads to an overlooked macroscopic particle migration, crucial for heterogeneous photocatalytic kinetics. Authors demonstrate self-driven electrophoresis of organic nanocrystals via rationally designed photogenerated outer electric field (OEF). [ABSTRACT FROM AUTHOR]

In the current study, a series of 1,3,4-oxadiazole and 1,2,4-triazole derivatives linked to quinazolinone were designed and synthesized by using Phase Transfer Catalysis. The structures of the synthesized compounds were confirmed by their IR, 1H NMR, 13C NMR, and HR-ESI-MS spectroscopic data, and their in vitro antiproliferative activities against A549, Hela, MCF-7 as well as L929 were detected by using CCK-8 assay. The results demonstrated that most of the compounds showed better growth inhibitory effect than 5-FU on A549, Hela, and MCF-7 cell lines. Especially, 2-(5-((3-bromophenyl)thio)-1,3,4-oxadiazole-2-yl)quinazolin-4(3H)-one (8o), 4-amino-5-((4-nitrophenyl)thio)-4H-1,2,4-triazol-3-yl)quinazolin-4(3H)-one (9m) and 2-(4-amino-5-(o-tolylthio)-4H-1,2,4-triazol-3-yl)quinazolin-4(3H)-one (9b) showed good antiproliferative activity against A549 cells with IC50 value of 3.46, 2.96, and 3.44 μM, respectively. 2-(4-Amino-5-((3,5-difluorophenyl)thio)-4H-1,2,4-triazol-3-yl)quinazolin-4(3H)-one (9h) and 4-amino-5-((4-nitrophenyl)thio)-4H-1,2,4-triazol-3-yl)quinazolin-4(3H)-one (9m) had obvious inhibitory effects on Hela cells with IC50 values of 1.76 and 3.91 μM, respectively. 2-(4-Amino-5-((2-chlorophenyl)thio)-4H-1,2,4-triazol-3-yl)quinazolin-4(3H)-one (9i) showed high inhibitory activity against MCF-7 cells with IC50 value of 2.72 μM. Meanwhile, all compounds showed lower cytotoxicity to L929 cells than positive control drug 5-FU. In development, according to the above preliminary observation, these novel quinazolinones incorporating 1,3,4-oxadiazole and 1,2,4-triazole thioether moieties could become potential molecular templates for searching new antitumor agents. [ABSTRACT FROM AUTHOR]

We show that the incorporation of a biotinylated Co(TAML) cofactor within streptavidin enables asymmetric radical-type oxygen atom transfer catalysis with improved activity and enantioselectivity. [ABSTRACT FROM AUTHOR]

Due to the electronic configuration of the atom and charge of the nucleus, the chlorine in organic molecules can exert a variety of effects. It can depart as a chloride anion in the process of substitution and elimination, facilitates the abstraction of protons and stabilizes generated carbanions, exerts moderate stabilizing effect of carbenes, carbocations and radicals. There are frequent cases where chlorine substituent promotes more than one transformation. These rich effects of chlorine substituent will be illustrated by examples of our work. [ABSTRACT FROM AUTHOR]

The recovery and reuse of the enantioselective catalysts produced by tedious work are important not only from the perspective of green chemistry, but also from the point of view of productivity. Some of the carbohydrate-based crown ethers prepared in our research group were able to generate significant asymmetric induction in certain cases. However, they were not recoverable after the synthesis. Therefore, we modified the most effective structure with a propargyl group so that it can be attached to a polymer with an azide–alkyne reaction. It was investigated whether the position of the bonding affects the activity of the crown ethers, hence, the propargyl group was introduced either to the side chain, to the anomeric center or to the benzylidene protecting group. To anchor the macrocycles, low molecular weight PVC was modified with azide groups in 4% and 10%, respectively. It was found that glucose-based crown ether bearing the propargyl group on the benzylidene unit and grafted to PVC in 4% has the highest activity regarding the enantioselectivity (77% ee). The catalyst was recoverable in the Michael addition of diethyl acetamidomalonate to nitrostyrene and it could be reused five times without the loss of enantioselectivity. [ABSTRACT FROM AUTHOR]

Liquid coordination complexes (LCCs), which are formed between metal halides and donor molecules, represent promising catalysts. Six amide-AlCl3 LCCs were successfully synthesized, followed by their characterization through NMR, Raman, and UV-visible spectroscopy. The acidity of these LCCs was quantified by performing computational modelling of fluoride ion affinities (FIA) and experimental Gutmann–Beckett measurements. Spectroscopic analysis indicated bidentate coordination between amide ligands and Al, which induced asymmetric splitting of Al2Cl6 into diverse ions such as [AlCl2L2]+, [AlCl4]−, [AlCl3L], and [Al2Cl6L]. The computed FIA was found to align well with the experimental acidity trends, thereby confirming the proposed structure of the LCC. In the alkylation tests, the LCC with a high acidity demonstrated an increase in the yields of C5-C7 alkylates. These results provide an in-depth understanding of the tuneable structures of amide-AlCl3 LCCs. The acidity of LCCs can be controlled by tuning the ratio of the organic ligand to AlCl3, which allows bidentate coordination to facilitate asymmetric splitting of Al2Cl6. The LCCs demonstrate a high degree of potential as versatile and sustainable acid catalysts in alkylation reactions. These findings may advance the foundational knowledge of LCCs for the purpose of targeted acid catalyst design. [ABSTRACT FROM AUTHOR]

Rotating packed beds (RPB) facilitate the mixing of heterogeneous substrates, and promote high mass transfer efficiency in heterogeneous reactions. For the enzymatic reactions, traditional porous particles with immobilized enzymes are sensitive to the strong sheer force of the RPB, thus limiting its application. This work offers a strategy for enzyme immobilization on the surface of stainless-steel fleece, to improve the shear strength resistance of immobilized enzymes. Lipase was applied to investigate and optimize the immobilization. Finally, a fatty acid hydratase (FAH) was applied for immobilization based on the optimized method, which was further applied for evaluating its performance in RPB. The results indicated that metal immobilized enzymes resist a higher shear force than their particle-immobilized alternatives. Operating at a centrifugal force factor (β) of 30, the hydration conversion rate of 96% is achieved after 8 h, which was from nearly 38% faster than in a stirrer tank reactor (hydration yield of 60%). The metal immobilization, moreover, efficiently improved the enzyme reusability, as demonstrated by a conversion rate remaining above 90% after 15 batches. These results indicated that a metal immobilization method combined with an RPB reactor significantly increases the efficiency of enzymatic reactions. [ABSTRACT FROM AUTHOR]

Chiral phosphonium salt catalysis, traditionally classified as a type of phase transfer catalysis, has proven to be a powerful strategy for the stereoselective preparation of diverse optically active molecules. However, there still remain numerous forbidding issues of reactivity and selectivity in such well‐known organocatalysis system. Accordingly, the development of new and high‐performance phosphonium salt catalysts with unique chiral backbones is highly desirable, yet challenging. This Minireview describes the prominent endeavours in the development of a new family of chiral peptide‐mimic phosphonium salt catalysts with multiple hydrogen‐bonding donors and their applications in a plethora of enantioselective synthesis during the past few years. Hopefully, this minireview will pave a way for further developing much more efficient and privileged chiral ligands/catalysts featuring exclusively catalytic ability in asymmetric synthesis. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) with high specific porosity, easy functionalization, and tailored structure are an emerging class of crystalline porous polymers that have been extensively exploited as ideal materials in various fields. Among them, sp2-carbon linked COFs with high chemical stability, porous backbone, and unique π-electron conjugated architectures structure have raised widespread attention. Specifically, the porous channels of olefin-linked COFs could be packed with active sites for catalysis and guest molecules, while π–π stacking interactions and conjugation systems pave the way for electron transfer. In recent years, many efforts have been devoted to the development of sp2-carbon linked COFs for applications in catalysis, energy storage, gas adsorption, and separation. In this review, we highlight the design principles, synthesis strategies, and impactful applications of olefin-linked COFs. We are looking forward to this review to deepen the understanding of the synthesis of olefin-linked COFs and motivate the further development of these novel conjugated organic materials with distinctive physicochemical properties, as well as their applications in a variety of fields. [ABSTRACT FROM AUTHOR]

Selective hydroarylation of dienes has potential to provide swift access to useful building blocks. However, most existing methods rely on dienes stabilised by an aromatic group and transmetallation or nucleophilic attack steps require electron‐rich aryl coupling partners. As such, there are few examples which tolerate wide‐spread heteroarenes such as pyridine. Whilst allylic C−H functionalisation could be considered an alternative approach, the positional selectivity of unsymmetrical substrates is hard to control. Here, we report a general approach for selective hydropyridylation of dienes under mild conditions using metal catalysed hydrogen‐atom transfer. Photoinduced, reductive conditions enable simultaneous formation of a cobalt‐hydride catalyst and the persistent radical of easily‐synthesised pyridyl phosphonium salts. This facilitates selective coupling of dienes in a traceless manner at the C4‐position of a wide‐range of pyridine substrates. The mildness of the method is underscored by its functional‐group tolerance and demonstrated by applications in late‐stage functionalisation. Based on a combination of experimental and computational studies, we propose a mechanistic pathway which proceeds through non‐reversible hydrogen‐atom transfer (HAT) from a cobalt hydride species which is uniquely selective for dienes in the presence of other olefins due to a much higher relative barrier associated with olefin HAT. [ABSTRACT FROM AUTHOR]

We, herein, report the synthesis of 13C2‐labeled natural products from the mugineic acid and avenic acid family. These phytosiderophores ("plant iron carriers") are built up from non‐proteinogenic amino acids and play a key role in micronutrient uptake in gramineous plants. In this work, two central building blocks are prepared from labeled starting materials (13C2‐bromoacetic acid, 13C2‐glycine) and further employed in our recently reported divergent, branched synthetic strategy delivering eight isotopically labeled phytosiderophores. The required labeled building blocks (13C2‐l‐allylglycine and a related hydroxylated derivative) were prepared via enantioselective phase‐transfer catalysis and enantio‐ and diastereoselective aldol condensation with a chiral auxiliary, respectively, both potentially valuable themselves for other synthetic routes toward labeled (natural) products. [ABSTRACT FROM AUTHOR]

Two novel N-alkylated isatin derivatives (2–3) were synthesized under phase-transfer catalysis conditions. Their condensation with hydrazine hydrate and phenylhydrazine in refluxing ethanol as solvent generates two series of isatin derivatives (3-hydrazono and 3-phenylhydrazono) (4–7). The structures synthesized are elucidated using UV/Vis, FTIR, 13C-NMR, 1H-NMR, and single crystal X-ray diffraction techniques of 2, 3, and 5. The experimental data were compared with the predicted ones obtained at the B3LYP/6-31G(d,p) level of theory. Relatively, good agreements were found between the calculated and experimental results. The intermolecular contacts in 2, 3, and 5 were investigated through the Hirshfeld surface analysis. The expected inhibitory efficiency of 2, 3, and 5 against cyclooxygenase-2 (COX-2) are investigated by their molecular docking into the binding site of COX-2, which revealed that 2 might have strong inhibition efficacy against COX-2 compared to 3. [ABSTRACT FROM AUTHOR]

Ethyl 5-methyl(1,2,4-triazolo[1,5-a]pyrimidin-7-yl)acetate : 1 has been used as a precursor for the synthesis of 1,2,4-triazolo[1,5-a]pyrimidine derivatives. Thus, the action of an excess of allyl bromide under liquid-solid phase transfer catalysis (PTC) conditions leads to ethyl 2-(5-methyl-(1,2,4-triazolo [1,5-a]pyrimidin-7-yl)-pent-4-enoate : 2 and ethyl 2-(prop-2-en-3-yl)-2-(5- methyl-(1,2,4-triazolo[1,5-a]pyrimidin-7-yl)-pent-4-enoate : 3 Moreover, the condensation of compound 1 with N,N-dimethylformamide-diethylacetal at reflux affords ethyl (2E)-3-dimethylamino-2-(5-methyl-1,2,4- triazolo[1,5-a]pyrimidin-7-yl)prop-2-enoate 4. Also 5-methyl-1,2,4-triazolo[1,5- a]pyrimidine 5 has been obtained during the condensation of compound 1 with di(2-chloroethyl)amine hydrochloride at reflux of DMF in the presence of potassium carbonate. A plausible mechanism has been proposed to explain the formation of triazolo[1,5-a]pyrimidine 5 involving an oxidation reaction of the methylene group of the side-chain in position 7 of the biheterocyclic compound. The structures of all compounds obtained have been elucidated on the basis of NMR spectroscopy and confirmed by a single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The condensation of the binucleophilic reagents hydrazine hydrate and hydroxylamine hydrochloride on 3-acetoacetyl-2-methyl-pyrido[1,2-a]pyrimidin-4-one 3 acting as a heterocyclic β-diketone affords 3-azolyl-2-methyl-pyrido[1,2-a]pyrimidine derivatives 4 and 7. The alkylation of 3-pyrazolyl-pyrido[1,2-a]pyrimidin-4-one with allyl bromide under phase transfer catalysis gives exclusively 3-[(1-prop-2-en-1-yl) 5-methypyrazol-3-yl]-2-methyl-pyrido[1,2-a] pyrimidin-4-one. A plausible mechanism for the formation of the obtained compounds 4 and 7 have been proposed and discussed. [ABSTRACT FROM AUTHOR]

1,n-(alkane-1,n-diyl)-bis-3-phenylhydrazono(hydroxyimino)-indolin-2- ones 12-17 have been synthesized from isatin. Thus, the condensation of isatin 1 with dibromoalcanes under liquid-solid phase transfer catalysis (PTC) conditions affords 1,n-bis-(isatin)alkanes which reacted with phenylhydrazine and hydroxylamine hydrochloride in refluxing ethanol. The structures of all compounds synthesized have been characterized by using ¹H NMR and 13C NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Poly-cotton fiber, a blend of polyester and cotton fiber, plays a significant role in the textile industry, with nearly 60% of Poly (ethylene Terephthalate) or PET being utilized for this purpose. However, the effective recovery of PET from textile waste remains a pressing concern, underscoring the importance of adopting greener methods over conventional ones. In this context, phase transfer catalysts have emerged as a promising novel approach in green chemistry. For instance, the use of Tetrabutylammonium bromides as catalysts in the alkaline hydrolysis process facilitates the separation of PET and recovery of TPA with an impressive 95% recovery rate at a relatively low temperature of 100°C. The escalating pace of industrialization coupled with evolving fashion trends has led to a substantial increase in poly-cotton waste generation. Consequently, focusing on the recovery of monomers for reuse not only addresses environmental concerns but also aligns with the fundamental principles of green chemistry, promoting sustainability within the textile sector. Thus, exploring and implementing innovative techniques like phase transfer catalysis can significantly contribute to mitigating environmental impacts while fostering efficient resource utilization in textile production. [ABSTRACT FROM AUTHOR]

Site‐specifically deuterated organocatalysts were prepared and found to show improved reactivity over the non‐deuterated analogs. Two privileged C2‐symmetric chiral binaphthyl‐modified tetraalkylammonium salts were selected for this study. The stability of these phase‐transfer catalysts was generally improved by site‐specific deuteration, though the degree of improvement was structure dependent. In particular, a large secondary kinetic isotope effect was observed for the tetradeuterated phase‐transfer catalyst. The performance of these deuterated catalysts in the asymmetric catalytic alkylation of amino acid derivatives was better than that of non‐deuterated analogs at low catalyst loadings. The results suggest that catalyst deuteration is a promising strategy for enhancing the stability and performance of organocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Photothermal catalysis is an innovative approach that integrates photochemical and thermocatalytic processes to enable an efficient use of full-spectrum sunlight in catalyzing various chemical reactions for energy conversion and environmental governance. This approach has demonstrated competitive performance and energy efficiency compared to conventional techniques, making it suitable for large-scale applications. In this review, we will comprehensively examine the fundamentals and classification of photothermal catalysis and discuss detailed design principles of various types of photothermal catalysts, focusing on enhancing solar light absorption, improving internal electric field for more energetic hot carriers (EHC) and localized thermal energy (LTE), interfacial engineering for robust and directed EHC transferring, and regulating EHC and LTE for continuous 24/7 operation. We will also report photothermal catalysis in a diverse range of chemical reactions. Moreover, we will introduce the latest technologies for synthesizing robust photothermal catalysts and advanced solar concentrators for pilot testing in the production of solar fuels at scale. Finally, the future opportunities and challenges of the promising but fledging field will be discussed, which is expected to transform conventional chemical industries into a clean and sustainable manner. [ABSTRACT FROM AUTHOR]

Carbohydrate-based macrocycles can be enantioselective catalysts in certain reactions. Previously, it was proven that the carbohydrate moiety could affect the catalytic activity of the monoaza-15-crown-5 type macrocycles derived from sugars. According to our experiments so far, the most effective enantioselective catalysts were the d-glucose- and the d-galactose-based crown ethers. To obtain more information about the effect of the carbohydrate unit, a rare monosaccharide, d-idose was incorporated into the monoaza-15-crown-5 structure. The key intermediates were methyl 4,6-O-benzylidene-α-d-idopyranoside and methyl 4,6-O-benzylidene-β-d-idopyranoside, which were synthesized from d-galactose. The efficiency of the idopyranoside-based crown compounds synthesized was investigated in asymmetric phase transfer reactions. In liquid-liquid biphasic reactions the highest enantioselectivity was 81% ee, while in solid-liquid phase systems the highest asymmetric induction was 67% ee. It was observed that the enantiodiscrimination was strongly dependent on the configuration of the anomeric center, on the side arm of the nitrogen, and on the structure of the substrate. [ABSTRACT FROM AUTHOR]

Chiral phase-transfer catalysis provides high level of enantiocontrol, however no experimental data showed the interaction of catalysts and substrates. 1 H NMR titration was carried out on Cinchona and Maruoka ammonium bromides vs. nitro, carbonyl, heterocycles, and N-F containing compounds. It was found that neutral organic species and quaternary ammonium salts interacted via an ensemble of catalyst + N-C-H and (sp2 )C-H, specific for each substrate studied. The correspondent BArF salts interacted with carbonyls via a diverse set of + N-C-H and (sp2 )C-H compared to bromides. This data suggests that BArF ammonium salts may display a different enantioselectivity profile. Although not providing quantitative data for the affinity constants, the data reported proofs that chiral ammonium salts coordinate with substrates, prior to transition state, through specific C-H positions in their structures, providing a new rational to rationalize the origin of enantioselectivity in their catalyses.

Although heterogeneous Fenton catalysis has captured increasing attention compared to its homogeneous counterpart, it still confronts some inherent drawbacks in use, such as the dilemma in solid-liquid separation and greater mass transfer resistance. Driven by the acoustic cavitation effect, herein, a sono-enhanced heterogeneous Fenton catalysis process was built to overcome the above two shortcomings, by rapidly synthesizing magnetic Fenton-like catalysts and accelerating electron transfer during the catalytic reaction. The results show that, compared to the traditional chemical coprecipitation method, Fe3O4 with smaller particle size and better crystallinity grew on the surface of halloysite nanotubes (HNTs) by using the sonochemical strategy, leading to displaying the higher catalytic activity toward the degradation of methylene blue (MB, improved by ~2.5 times). In parallel, more •OH and •O2− were produced after the ultrasound was further introduced to the routine Fenton-like catalysis system, thus highly accelerating the removal of MB (improved by ~50%). Besides, benefiting from the robust chemical integration of Fe3O4 and HNTs, Fe3O4@HNTs-S had a lower iron ion leaching in use, showing superior catalytic stability. The speed, simplicity, and generality, together with the enhanced mass transfer rate, make the use of ultrasound an enabling methodology to improve the heterogeneous Fenton catalysis. [ABSTRACT FROM AUTHOR]

Dispersing metal‐organic framework (MOF) solids in stable colloids is crucial for their availability and processibility. Herein, we report a crown ether surface coordination approach for functionalizing the surface‐exposed metal sites of MOF particles with amphiphilic carboxylated crown ether (CEC). The surface‐bound crown ethers significantly improve MOF solvation without compromising the accessible voids. We demonstrate that CEC‐coated MOFs exhibit exceptional colloidal dispersibility and stability in 11 distinct solvents and six polymer matrices with a wide range of polarities. The MOF‐CEC can be instantaneously suspended in immiscible two‐phase solvents as an effective phase‐transfer catalyst and can form various uniform membranes with enhanced adsorption and separation performance, which highlights the effectiveness of crown ether coating. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The direct use of non‐prefunctionalized arene and alkane as the starting materials to construct Caryl−Calkyl bond is an unfulfilled target and approaches to this challenge rarely surface in methodology studies. Current methods for thermocatalytic arene‐alkane couplings (AAC) occur with specific substrates and/or inconvenient reagents. Herein, we report a one‐pot relay bicatalysis system for AAC involving (pincer)Ir‐catalyzed alkane transfer dehydrogenation and Fe(OTf)3‐catalyzed olefin hydroarylation. This system exhibits broad scope and is particularly effective for alkylation of arenes with arylalkanes to form 1,1‐diarylalkanes with high chemo‐ and regioselectivity, making it potentially useful for late‐stage alkylation of complex molecules. Experimental mechanistic data provide a view into the factors controlling the regioselectivity. Finally, the strategy of dehydrogenation‐enabled arene‐alkane couplings has been successfully extended to a tandem catalysis by using a heterogeneous olefin hydroarylation catalyst. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The direct use of non‐prefunctionalized arene and alkane as the starting materials to construct Caryl−Calkyl bond is an unfulfilled target and approaches to this challenge rarely surface in methodology studies. Current methods for thermocatalytic arene‐alkane couplings (AAC) occur with specific substrates and/or inconvenient reagents. Herein, we report a one‐pot relay bicatalysis system for AAC involving (pincer)Ir‐catalyzed alkane transfer dehydrogenation and Fe(OTf)3‐catalyzed olefin hydroarylation. This system exhibits broad scope and is particularly effective for alkylation of arenes with arylalkanes to form 1,1‐diarylalkanes with high chemo‐ and regioselectivity, making it potentially useful for late‐stage alkylation of complex molecules. Experimental mechanistic data provide a view into the factors controlling the regioselectivity. Finally, the strategy of dehydrogenation‐enabled arene‐alkane couplings has been successfully extended to a tandem catalysis by using a heterogeneous olefin hydroarylation catalyst. [ABSTRACT FROM AUTHOR]

To reduce the emission of NO from fossil fuel combustion and the energy consumption associated with NH3 production, the development of simple and efficient methods to transform NO into high-value-added NH3 is essential. Here, we report the efficient catalytic hydrogenation of NO to NH3 under mild reaction conditions by the synergistic catalysis of functionalized ionic liquids (FILs) and Pd catalysts. In this system, an FIL [TEPA][Im] acted as both an absorbent and a catalyst. The presence of [TEPA][Im] enhanced the catalytic performance by changing the coordination and electronic environment of Pd on the Pd/C catalyst. First, NO was absorbed by [TEPA][Im]; then, the hydrogenation of absorbed NO to NH3 was performed at a low temperature via the synergistic catalyzation of [TEPA][Im] and Pd/C. The effects of various factors on NO hydrogenation to NH3 were also investigated. Remarkably, Pd/C exhibited outstanding properties in the formation of NH3 with a high yield of 67% in the FIL [TEPA][Im] under the conditions of 100 °C and an H2 pressure of 0.5 MPa. [TEPA][Im] could be reused multiple times and the product NH3 could be recovered by flashing. [ABSTRACT FROM AUTHOR]

The review presents a comparative analysis of promising homogeneous metal complex catalysts and the results of studies on the synthesis and determination of the structural characteristics of efficient catalysts for the oxidation of organic compounds with hydrogen peroxide Q3{PO4[WO(O2)2]4} (Q is the quaternary ammonium cation) by EXAFS, SAXS, NMR, Raman, and IR spectroscopy. The possibilities of using bifunctional homogeneous peroxopolyoxo metal complexes in combination with organic cations having quaternized nitrogen under conditions of phase transfer catalysis were considered using as an example the oxidation of organic compounds of various classes with hydrogen peroxide, forming aliphatic and aromatic epoxides, mono- and dicarboxylic acids, as well as biologically active compounds for medical and agroindustrial purposes. [ABSTRACT FROM AUTHOR]