Search

Triptolide, a bioactive diterpene tri-epoxide extracted from Tripterygium wilfordii Hook F (TWHF), exhibits notable pharmacological activities, including anti-inflammatory, immunosuppressive, antifertility, and anticancer effects. Despite its promising therapeutic potential, clinical applications of triptolide are significantly limited by its poor water solubility and substantial toxicity, particularly hepatotoxicity, nephrotoxicity, and cardiotoxicity. These toxic effects are difficult to separate from many of its desired therapeutic effects, the Yin and Yang of triptolide applications. Triptolides therapeutic and toxic effects are linked to its inhibitory interactions with XPB, a DNA helicase essential for transcription by RNA polymerase II (RNAPII) and nucleotide excision repair (NER). By irreversibly binding to XPB, triptolide inhibits its ATPase activity, leading to global repression of transcription and impaired NER, which underlies its cytotoxic and antitumor properties. Recent developments, including triptolide prodrugs such as Minnelide and derivatives like glutriptolides, aim to enhance its pharmacokinetic properties and reduce toxicity. This review critically examines triptolides chemical structure, therapeutic applications, toxicological profile, and molecular interactions with XPB and other protein targets to inform future strategies that maximize therapeutic efficacy while minimizing adverse effects.

Drugs that inhibit HIV transcription and/or reactivation of latent HIV have been proposed as a strategy to reduce HIV-associated immune activation or to achieve a functional cure, yet comparative studies are lacking. We evaluated 26 drugs, including drugs previously reported to inhibit HIV transcription (inhibitors of Tat-dependent HIV transcription, Rev, HSF-1/PTEF-b, HSP90, Jak/Stat, or SIRT1/Tat deacetylation) and other agents that were not tested before (inhibitors of PKC, NF-κB, SP-1, or histone acetyltransferase; NR2F1 agonists), elongation (inhibitors of CDK9/ PTEF-b), completion (inhibitors of PolyA-polymerase), or splicing (inhibitors of human splice factors). To investigate if those drugs would vary in their ability to affect different blocks to HIV transcription, we measured levels of initiated, elongated, midtranscribed, completed, and multiply spliced HIV RNA in PBMCs from antiretroviral therapy-suppressed individuals following ex vivo treatment with each drug and subsequent T cell activation. We identified new drugs that prevent HIV reactivation, including CDK and splicing inhibitors. While some drugs inhibited 1 or 2 steps, other drugs (CDK inhibitors, splicing inhibitors, tanespimycin, and triptolide) inhibited multiple stages of HIV transcription and blocked the production of supernatant viral RNA. These drugs and targets deserve further study in strategies aimed at reducing HIV-associated immune activation or achieving a functional cure.

Allogeneic hematopoietic stem cell transplantation (aHSCT) can cure patients with otherwise fatal leukemias and lymphomas. However, the benefits of aHSCT are limited by graft-versus-host disease (GVHD). Minnelide, a water-soluble analog of triptolide, has demonstrated potent antiinflammatory and antitumor activity in several preclinical models and has proven both safe and efficacious in clinical trials for advanced gastrointestinal malignancies. Here, we tested the effectiveness of Minnelide in preventing acute GVHD as compared with posttransplant cyclophosphamide (PTCy). Strikingly, we found Minnelide improved survival, weight loss, and clinical scores in an MHC-mismatched model of aHSCT. These benefits were also apparent in minor MHC-matched aHSCT and xenogeneic HSCT models. Minnelide was comparable to PTCy in terms of survival, GVHD clinical score, and colonic length. Notably, in addition to decreased donor T cell infiltration early after aHSCT, several regulatory cell populations, including Tregs, ILC2s, and myeloid-derived stem cells in the colon were increased, which together may account for Minnelides GVHD suppression after aHSCT. Importantly, Minnelides GVHD prevention was accompanied by preservation of graft-versus-tumor activity. As Minnelide possesses anti-acute myeloid leukemia (anti-AML) activity and is being applied in clinical trials, together with the present findings, we conclude that this compound might provide a new approach for patients with AML undergoing aHSCT.

We report a useful synthetic approach to assemble in/in epoxide, in/out epoxide, and out/out epoxide in cage systems using the Corey–Chaykovsky reaction and the Peterson olefination as key steps. In this regard, a variety of pentacycloundecane (PCUD) based cage compounds containing oxirane rings with diverse stereochemical disposition were synthesized via a simple synthetic sequence. Five cage diones were used for this purpose, and the starting cage diones were prepared with easily accessible starting materials such as 1,4-hydroquinone derivatives and cyclopentadiene. Here, we have used the Diels–Alder (DA) reaction, a [2+2] photocycloaddition, the Corey–Chaykovsky reaction, and the Peterson olefination as crucial steps to prepare the target molecules. [ABSTRACT FROM AUTHOR]

Fan-out (FO) packages are in high demand for smartphones and Internet of Things (IoT) devices because they allow for the integration of multiple components within a single package, leading to enhanced functionality and improved operational performance. In addition, the shift from solder bumps to copper pillar bumps for interconnection is expected to become a prevalent trend in FO package assemblies because of their superior electrical and thermal performance and ability to achieve a finer pitch. However, the increased stiffness of the copper pillars increases the risk of interface fractures between the pillars and solder bumps during the surface mount technology process, which may degrade the thermal cycle test (TCT) reliability. Consequently, the present study develops a three-dimensional (3D) computational model, which approximates the thermomechanical properties of the redistribution layer (RDL) using the rule of mixtures principle, to analyze the reliability of the Cu pillar bumps in FO packages under thermal cycling between −55°C and 125°C. The tensile stress–strain properties of the polyimide (PI) film in the FO package are determined experimentally using an MTS Acumen microforce tester. The experimental data are used to construct an empirical formula for predicting the stress–strain response of the PI film, which is then incorporated into the simulation model. The validity of the simulation model is confirmed by comparing the predicted results for the out-of-plane deformation of the FO package with experimental observations. The reliability of the Cu pillar bumps under TCT processing is investigated numerically using the Anand viscoplastic constitutive model. Finally, a second-order response surface methodology model and Box–Wilson central composite design method are employed to determine the optimal design of the FO package that minimizes the plastic work density of the Cu pillar bumps. The results show that the thermomechanical reliability of the FO package depends mainly on the Cu trace coverage in the RDL and the thickness of the epoxy molding compound layer. [ABSTRACT FROM AUTHOR]

Herein, we have reported an effective protocol for the regioselective transfer hydrogenation (TH) of epoxides by utilizing a phosphine‐free bis‐NHC−Mn(I) complex and ammonia borane. By employing this strategy, aromatic epoxides were selectively converted to primary alcohols whereas secondary alcohols were obtained exclusively from aliphatic epoxides. The protocol was further extended for the TH of azoarenes and nitroarenes to hydrazoarenes and anilines respectively. Notably, a library of substrates with different functional groups were screened which resulted in the corresponding transfer hydrogenated product in good to excellent yields. A series of mechanistic investigations were carried out to understand the catalytic process. [ABSTRACT FROM AUTHOR]

A Palladium catalyzed C4‐ alkylation of indoles using epoxide as an alkylating agent and pivaloyl as a weak chelating group has been demonstrated. A variety of substituted epoxides and indoles furnished the desired β‐indolylethyl alcohols in 38%–87% yields. Control experiments indicate that the C−H cleavage step is irreversible. The resultant hydroxyl group has been converted to various functional groups to demonstrate the synthetic utility of this protocol. [ABSTRACT FROM AUTHOR]

Chiral organofluorine compounds featuring a monofluoromethyl (CH2F)-substituted stereocenter are often encountered in a number of drugs and bioactive molecules. Consequently, the development of catalytic asymmetric methods for the enantioselective construction of CH2F-substituted stereocenters has made great progress over the past two decades, and a variety of enantioselective transformations have been accordingly established. According to the types of fluorinated reagents or substrates employed, these protocols can be divided into the following major categories: (i) enantioselective ring opening of epoxides or azetidinium salts by fluoride anions; (ii) asymmetric monofluoromethylation with 1-fluorobis(phenylsulfonyl)methane; (iii) asymmetric fluorocyclization of functionalized alkenes with Selectfluor; and (iv) asymmetric transformations involving α-CH2F ketones, α-CH2F alkenes, or other CH2F-containing substrates. This feature article aims to summarize these recent advances and discusses the possible reaction mechanisms, advantages and limitations of each protocol and their applications. Synthetic opportunities still open for further development are illustrated as well. This review article will be an inspiration for researchers engaged in asymmetric catalysis, organofluorine chemistry, and medicinal chemistry. [ABSTRACT FROM AUTHOR]

The synthesis of copper nanocrystals on tartaric acid jute composite surface is reported. The formation of nanocrystals is detected by FT IR, Powder X‐ray diffraction, SEM, and TEM analysis. The average size of the nanocrystals is found to be 500 nm. The reaction of the copper nanocrystals with CO2 resulted in a decrease in the size of the nanoparticles. Cycloaddition reaction of epoxides to cyclic carbonate is efficiently carried out by the copper nanocrystals on tartaric acid jute composite surface (CUNPJT) without using any cocatalyst and solvent. To the best of author's knowledge, this is the first example of copper nanocrystals catalyzing the cycloaddition of CO2 and epoxide. [ABSTRACT FROM AUTHOR]

The sequestration of atmospheric CO2 into value-added products is of great interest from economic and environmental perspectives. The tetra-shelled Cr1.3Fe0.7O3 hollow sphere as a heterogeneous catalyst was synthesized by a simple hydrothermal method followed by calcination at 600 °C. The synthesized tetra-shelled hollow spheres were characterized by several effective tools. The catalytic performance was studied for the cycloaddition reaction of CO2 with epoxides under solvent-free conditions. The reaction time, reaction temperature, CO2 pressure, and the catalyst amount were systematically studied. Under the best-experimented condition (0.02 g of the catalyst, 80 °C, 6 h, and 4 bar CO2 pressure), the catalyst demonstrated a broad substrate scope and functional group tolerance. Besides, the catalyst showed high recycling efficiency for five consecutive reaction cycles with no significant decline in activity. [ABSTRACT FROM AUTHOR]

A synthetic protocol for the preparation of novel 3,4‐pyrrolidine‐fused β‐lactams was developed. The proposed 2,6‐diazabicyclo[3.2.0]heptan‐7‐one scaffolds were constructed through an amido group‐induced, potassium tert‐butoxide‐promoted intramolecular ring closure of 3‐acylamino‐4‐oxiranyl‐β‐lactams as the key reaction step. Alternatively, the desired cyclization was also effected by means of a scandium triflate‐mediated catalytic approach. In this way, a set of stereodefined 3,4‐pyrrolidine‐fused β‐lactams was synthesized, which were preliminary evaluated as β‐lactamase inhibitors. These first‐line biological assessments led to the identification of a 2‐benzoyl‐6‐(4‐methoxyphenyl)‐substituted diazabicyclo structure as an eligible starting point for further β‐lactamase inhibitor optimization studies. [ABSTRACT FROM AUTHOR]

ABSTRACT New reaction systems “oxirane – nucleophile X– – proton‐donor reagent AH – solvent” have been proposed for the detection of epoxides in which nucleophilic opening of the oxirane ring occurs accompanied by the formation of a colored product. The kinetic and mechanistic regularities of reactions in the proposed systems were investigated. Reaction orders with respect to the components of the systems have been determined: close to 1 – for oxirane and X−, close to 0 – for AH. It was shown that the proposed chromogenic reactions represent nucleophilic substitution of SN2‐type and allow the detection of epoxides containing both a terminal and internal epoxy group, which can be used to monitor processes in systems where epoxides are either the initial compounds or the synthesis products. Based on the conducted studies, it is possible to develop methods for the quantitative determination of epoxides using kinetic methods of analysis and UV–visible spectroscopy. [ABSTRACT FROM AUTHOR]

Cr(III) metal centers have been successfully incorporated in the terephthalaldehyde-triaminoguanidium chloride COP, Te-TGCl. Free COP, Te-TGCl and metalated COP, Te-TG-Cr(III) were characterized with the help of various techniques, viz., FT-IR, 13C CP-MAS NMR, PXRD, XPS, FESEM, SEM-EDX, HR-TEM, TGA and BET. Due to the presence of the Lewis acidic Cr(III) center, Te-TG-Cr(III) showed superior activity (ECH, 99% conv.) compared to non-metalated COP, Te-TGCl (ECH, 75% conv.) in the cycloaddition reaction of CO2 to epoxides, which resulted in chemically valuable cyclic carbonate products. Moreover, compared to Cr(NO3)3·9H2O (ECH, 45% conv.), COP-immobilized Cr(III), Te-TG-Cr(III), shows much higher activity (ECH, 99% conv.), signifying the importance of COP in the enhancement of catalytic activity. Moreover, Te-TG-Cr(III) discriminates the substrates on the basis of the length of the epoxide side chains, showing much higher conversions for smaller substrates ECH and EBH (99% and 96% conv., respectively) compared to larger substrates BGE, AGE, PGE, EH and SO (68%, 60%, 69%, 57% and 35% conv., respectively). [ABSTRACT FROM AUTHOR]

The past few decades have witnessed tremendous development within epoxides. Among the many known reactions involving epoxide, Meinwald rearrangements represent one of the most important and attractive approaches, which can transform epoxides into versatile carbonyl compounds. Given the high efficiency of this protocol, substantial efforts have been made by researchers by utilizing multiple catalyst systems. This review provides an overview of recent advances in the Meinwald rearrangement (from 2014 onward), along with detailed discussions on mechanistic insights. This review aims to highlight the importance and value of these methodologies, thereby promoting further investigation and application. [ABSTRACT FROM AUTHOR]

Dendritic ZSM-5 zeolites were investigated in the isomerization of monoterpene epoxides, including limonene-1,2-epoxide (LE), α-pinene epoxide, and β-pinene epoxide, which yields high-value compounds used in fragrances, cosmetics, and pharmaceuticals. The fresh catalysts were thoroughly characterized using XRD, Ar physisorption, pyridine-FTIR, TEM, FTIR/DTBPyr, and 27Al MAS NMR. In comparison with conventional and hierarchical ZSM-5 materials, the dendritic zeolite with a crystallization time of 4 days (d-ZSM-5/4d) was the most active material, with a turnover frequency value of 4.4 min−1 for LE isomerization. Likewise, remarkable yields of dihydrocarvone (DHC, 63%, 70 °C, 2 h), campholenic aldehyde (72.4%, 70 °C, 5 min), and myrtanal (47.7%, 50 °C, 5 min) were obtained with this material that exhibited the largest mesopore/external surface area (360 m2 g−1), showing also the narrowest mesopore size distribution. A direct relationship was observed between the TOF values and the concentration of external Brønsted acid sites, showing the presence of strong steric/diffusional limitations that are greatly overcome with the dendritic zeolites. The lower reactivity of trans-LE compared to cis-LE was attributed to the larger steric hindrance of the oxygen atom. Exploration of the solvent influence revealed that the reaction rate of LE was favored by non-polar solvents, while highly selective DHC formation occurred in the solvents of medium polarity. The d-ZSM-5/4d sample was shown to be robust because catalytic activity could be completely recovered by air calcination. [ABSTRACT FROM AUTHOR]

We present the use of an amine functionalized two-dimensional clay i.e., aminoclay (AC), in the chemistry of a three-dimensional metal–organic framework (MOF) i.e., MIL-101(Cr), to prepare MIL-101(Cr)/AC composites, which are exploited as catalysts for efficient conversion of CO2 gas into cyclic carbonates under ambient reaction conditions. Three different MOF nanocomposites, denoted as MIL-101(Cr)/AC-1, MIL-101(Cr)/AC-2, and MIL-101(Cr)/AC-3, were synthesized by an in situ process by adding different amounts of AC to the precursor solutions of the MIL-101(Cr). The composites were characterized by various techniques such as FT-IR, PXRD, FESEM, EDX, TGA, N2 adsorption, as well as CO2 and NH3-TPD measurements. The composites were exploited as heterogeneous catalysts for CO2 cycloaddition reactions with different epoxides and the catalytic activity was investigated at atmospheric pressure under solvent-free conditions. Among all the materials, MIL-101(Cr)/AC-2 shows the best catalytic efficiency under the optimized conditions and exhibits enhanced efficacy compared to various MIL-101(Cr)-based MOF catalysts, which typically need either high temperature and pressure or a longer reaction time or a combination of all the parameters. The present protocol using MIL-101(Cr)/AC-2 as the heterogeneous catalyst gives 99.9% conversion for all the substrates into the products at atmospheric pressure. [ABSTRACT FROM AUTHOR]

Cycloaliphatic epoxides exhibit post‐light irradiation heat‐induced polymerization, creating warp‐resistant green bodies during sintering. However, their use in light polymerization three‐dimensional (3D) printing is limited by slow photo‐curing speeds. In this study, a photo‐cationic polymerizable ceramic slurry was developed for 3D printing by mixing oxetane with cyclo‐aliphatic epoxide. This mixture improved photo‐curing speed, reduced resin viscosity, and enhanced the ceramic slurry's solid content. Additionally, we optimized the slurry by considering the specific and content ratio of photosensitizers and light absorbers. The optimized slurry polymerized unreacted functional groups in the polymer, improving the fracture strength of the green bodies through enhanced crosslinking density and uniformity in each layer. Ultimately, a sintered body without warpage was produced by the improved green bodies. This approach provides a solution related to controlling the photocuring speed and expands the potential applications of 3D printing in areas where the precision and stability of the printing material are required. [ABSTRACT FROM AUTHOR]

Various configurations of adhesive joints exist, each with unique characteristics. In the case of peel load solicitations, T-joints are the most common choice but are not sufficiently addressed in the literature, especially regarding the geometrical and material influence on their performance. Recently, meshless methods, like the Radial Point Interpolation Method (RPIM), have been used as alternatives to the Finite Element Method (FEM) for investigating joint behaviours. The present work aims to study the free length (FL) effect in T-joints, which is related to substrate stiffness. Three distinct FL dimensions were evaluated. At the same time, the effect of tp2 and adhesive type were taken into account. Initially, joint strength (Pmax) was predicted using two numerical approaches: FEM and RPIM, both employing elastic-plastic material models. Subsequently, the results were compared with the experimental data. Moreover, two yield criteria were considered to analyse the adhesive: von Mises and the Exponential Drucker-Prager criteria. The data resultant from this first phase was then used to select the correct yield criterion for evaluating the influence of FL in the adhesive joints. The methodology was validated, and then geometrical and material design recommendations were presented for the efficient use of T-joints in structural applications. [ABSTRACT FROM AUTHOR]

Employing enzymatic reaction cascade principles to synthesize artificial materials with multiple autonomously operating active sites is one of the holy grails in modern catalysis research. In this regard, metal–organic frameworks (MOFs) are promising host platforms. Yet, applying MOFs as enzyme‐mimicking catalysts is synthetically challenging. Herein, we present a design strategy for the synthesis of porphyrin‐based MOFs for the cascade catalysis of the conversion of olefins to epoxides and their cycloaddition with CO2 to cyclic carbonates. The MOFs feature tunable dual active sites with synthetically controllable metal variations. A clear dependence of the metal combination on the catalytic performance of the MOF catalysts is shown. This work advances the understanding essential for designing sophisticated, multifunctional porphyrin MOFs for efficient one‐pot cascade catalysis. [ABSTRACT FROM AUTHOR]

This study presents an organocatalytic C−H functionalization approach for postpolymerization modification (PPM) of poly(ethylene oxide) (PEO). Most of PEO PPM is previously processed at the end hydroxy group, but recent advances in C‐H functionalization open a way to modify the backbone position. Structurally diverse carboxylic acids are attached to PEO through a cascade process of radical generation by peroxide and oxidation to oxocarbenium by tertiary butylammonium iodide. Attaching carboxylic acids yields a series of functionalize PEO with acetal units (2−5 mol%) in a backbone, which is not accessible via conventional copolymerization of epoxides. The optimized conditions minimizes the uncontrolled degradation or crosslinking from the highly reactive radical and oxocarbenium intermediate. The newly introduced acetal units bring degradability of PEO as well as delivery of carboxylic acid molecules. Hydrolysis studies with high molecular weight functionalization PEO (Mn = 13.0 kg mol−1) confirm the steady release of fragmented PEO (Mn ∼ 2.0 kg mol−1) and carboxylic acid over days and the process rate is not sensitive to pH variation between pH 5 and 9. The presented method offers a versatile and efficient way to modify PEO with potential energy and medical applications. [ABSTRACT FROM AUTHOR]

Ambient condition-determined chemical CO2 fixation affords great promise for remitting the pressure of CO2 release. The construction of a microporous environment easily captures CO2 molecules around the reactive sites of the catalyst to reinforce the reaction process. Herein, multi-hydroxyl-containing hyper-crosslinked organic polymers (HCPs-OH-n) are synthesized by the polymerization of 1,4-dichlorobenzyl (DCX) and m-trihydroxybenzene in the monosaccharide form in a Friedel–Crafts alkylation hypercrosslinking process (FCAHP). By tuning the DCX ratio in the FCAHP, the structural properties can be regulated to create a more microporous surface in the HCPs-OH-n; meanwhile, the formed multi-hydroxyl species in the microporous environment could induce the easy interaction between hydroxyls and epoxides by forming a hydrogen bond, which improves the activation of epoxides during the cycloaddition reaction to synthesize the cyclic carbonates at ambient conditions. The structural properties suggest that HCPs-OH-n possess a large surface area with appreciable microporous and mesoporous distribution. As expected, the HCPs-OH-3 bearing the most abundant mesoporosity affords the highest reactivity in the chemical CO2 fixation to cyclic carbonates and is endowed with rational recoverability. [ABSTRACT FROM AUTHOR]

This study investigated the manufacturing processes for structural supercapacitors (SSCs) using smear molding (RS), resin transfer molding (RTM), and vacuum-assisted resin transfer molding (VARTM). Woven carbon fibers were used as the electrode, woven glass fibers as an insulating layer, and an alkaline/epoxy compound as the electrolyte. In the RTM process, due to the vacuum and the high-pressure injection of the electrolyte, the electrochemical and mechanical properties of the SSC can be greatly improved, and the void contents in the SSC can be reduced. The balanced electrochemical performance and mechanical properties of SSCs were observed in the range of epoxy content from 15 wt% to 30 wt%. This study contributes to the development of SSCs through the establishment of the fabrication process for improvements in part quality. The fabrication method demonstrated here can be directly applied by industries to produce even larger-scale SSCs, opening up new possibilities for practical implementation and scalability. [ABSTRACT FROM AUTHOR]

The crystalline sponge method has proven invaluable in the preparation and analysis of supramolecular host/guest complexes if the host can be obtained in a suitable crystalline form, allowing the analysis of guest binding modes inside host cavities which can inform other studies into processes such as catalysis. Here, we report the structures of a set of ten host/guest complexes using an octanuclear coordination cage host with a range of small-molecule neutral organic guests including four aromatic aldehydes and ketones, three cyclic lactams, and three epoxides. In all cases, the cavity-bound guests are anchored by a collection of CH•••O hydrogen-bonding interactions between an O atom on the guest and a convergent set of CH protons at a pocket on the cage interior surface. Depending on guest size and the presence of solvent molecules as additional guests, there may be one or two cavity-bound guests, with small aromatic guests forming π-stacked pairs. Some guests (the lactams) participate in additional NH•••F H-bonding interactions with surface-bound fluoroborate anions, which indicate the type of anion/guest interactions thought to be responsible for solution-phase catalytic reactions of bound guests. [ABSTRACT FROM AUTHOR]

H-bond donor (HBD) catalysis is essential in the cycloaddition of CO2 with epoxide (CCE) where a strong HBD is prevalent; however, current C–H H-bond donors are extremely weak and scarcely viable in catalysis. We reveal sulfonium featuring multiple α-C–H bonds as a new type of efficient HBD catalyst in the CCE reaction. Two series of cyclic tertiary sulfoniums were designed and evaluated in the cycloaddition of CO2 to epoxide. An optimal S-alkyl tetrahydrothiophenium bromide (THT3-Br) catalyst converted epoxides to the corresponding cyclic carbonates with high conversion (>90%) and near quantitative selectivity (99%) in 6 h under 1 MPa pressure of CO2, at 100 °C, and with 5 mol% loading. NMR titration confirmed the triple H-bonding of the α-C–H of sulfonium to epoxide, which activated the substrate oxirane and facilitated bromide attack on the methylene carbon. The first observation of sulfonium in catalytic CCE reactions suggested a wider application of C–H H-bonding catalysis in carbon dioxide fixation. [ABSTRACT FROM AUTHOR]

Cyclophellitol is a potent and selective mechanism‐based retaining β‐glucosidase inhibitor that has served as a versatile starting point for the development of activity‐based glycosidase probes (ABPs). We developed routes of synthesis of eight mono‐ and dideoxycyclophellitols and cyclophellitol aziridines, the latter as ABPs carrying either a biotin or fluorophore linked to the aziridine nitrogen. We reveal the potency of these 24 compounds as inhibitors of the three human retaining β‐glucosidases, GBA1, GBA2 and GBA3. We show that 3,6‐dideoxy‐β‐galacto‐cyclophellitol aziridine selectively captures GBA3 over GBA1 and GBA2 in extracts of cells overexpressing both GBA2 and GBA3. We also identify a probe that selectively labels GBA1 and GBA2 over GBA3 at lower concentrations. In sum, the here‐presented studies reveal new chemistries to prepare chiral, substituted cyclitol epoxides and aziridines, add to the growing suite of cyclophellitols varying in configuration and substitution pattern, and yielded a reagent that may find use to investigate the physiological role and therapeutic relevance of the most elusive of the three retaining β‐glucosidases: GBA3. [ABSTRACT FROM AUTHOR]

Epoxides are high‐valued intermediates in the production of chemicals, pharmaceuticals, perfumes, and polymers. Given the growing demand for epoxides, it is imperative to develop more environmental friendly and sustainable routes instead of the chlorohydrin process. Notably, the direct utilization of hydrogen peroxide (H2O2) for the epoxidation reaction presents significant advantages from both environmental and economic perspectives. The review provides insights into both homogeneous and heterogeneous catalysts employed in the 1‐butene epoxidation using the green oxidant H2O2. Among the diverse range of catalysts, titanosilicate‐1 (TS‐1) has garnered extensive attention due to its exceptional selectivity and high oxygen atom utilization. The aim of this review is to illustrate various strategies for TS‐1 catalysts preparation that can lead to more versatile, higher‐performance, and greener epoxidation processes. Additionally, various potential approaches to enhance the catalyst performance of TS‐1 are highlighted, including (i) constructing specific coordination modes of Ti sites, (ii) regulating the microenvironment around Ti sites, and (iii) improving the accessibility of Ti sites. Furthermore, advances in molding TS‐1 catalysts are also introduced from the perspective of the industrialization. Finally, future research directions are discussed with emphasis on the application scope of TS‐1 to gain deeper insights into epoxidation process. [ABSTRACT FROM AUTHOR]

ABSTRACT This study highlights the synergistic interplay between a Lewis acidic copper ion and a dissociated ligand from Cu(triNHC) complexes in the synthesis of cyclic carbonates from CO2 and epoxy compounds. The reactions were found to proceed efficiently under Cu(triNHC)‐catalyzed conditions, yielding significant quantities of cyclic carbonates across various epoxy substrates encompassing amine, sulfide, and ether functionalities. Stereochemical analyses underscore a pronounced propensity for retaining the stereochemistry of epoxy compounds in the resultant carbonates. This suggests a mechanism involving double inversion of stereochemistry during the reaction, which comprises catalyst‐mediated epoxide ring opening, subsequent CO2 addition, and carbonate ring closing. These findings align with established mechanisms for CO2 fixation reactions, shedding light on the intricate pathways underlying this catalytic process. [ABSTRACT FROM AUTHOR]

Arylazo sulfones were used as Photoacid Generators (PAGs) for the visible-light photorelease of strong sulfonic acids to promote the ring opening of epoxides in benign media (DMC/water mixtures) or under neat conditions. Water, alcohols, azide and thiocyanate anions, as well as electron-rich aromatics were used in the role of the nucleophile. The resulting 1,2-disubstituted adducts were formed mostly in >99% yield in a high regioselective fashion. [ABSTRACT FROM AUTHOR]

The development of greener methods for the preparation of three‐membered rings has increased in the last decade, not only due to their biological activity but also to the ring strain of those heterocycles that make them useful precursors of more complex molecules. In this work, the visible‐light‐promoted synthesis and ring‐opening of aziridines and epoxides, reported in the last five years, were reviewed. Both homogeneous and heterogeneous catalysts were discussed and, in addition, the plausible mechanism pathways were highlighted. [ABSTRACT FROM AUTHOR]

This paper discusses web slenderness effects on the flexural behaviour of epoxy adhesive-bonded compound normal and high-strength steel beams. The compound beams were simply supported and consisted of an I-section connected, on its top flange, to a channel section using an epoxy adhesive. A non-linear three-dimensional finite-element modelling study was performed using Abaqus software for the analysis of the beams. The non-linear finite-element modelling was verified against tests on compound steel beams with different cross-sections. An extensive parametric study was carried out using the finite-element modelling to study the effects of the change in web slenderness, cross-sectional geometries, beam lengths and steel strengths on the flexural behaviour of compound steel beams. The failure moments predicted by the finite-element modelling were compared with the design moments predicted by the European code for steel beams in flexure. It is shown that the code generally overestimated the design failure moments for most of the epoxy adhesive-bonded compound steel beams investigated in this study. In addition, reliability analysis was performed to assess the reliability of the design rules of the code. Generally, it was found that the European code is unconservative and statistically unreliable for the epoxy adhesive-bonded compound beams investigated in this study. [ABSTRACT FROM AUTHOR]

Protective polymer composite coatings are widely used in marine transport owing to their improved adhesion and cohesion properties. Modifiers are introduced to enhance the performance characteristics of polymer coatings based on epoxy binders. This study investigates the impact of the eco-friendly nano modifying additive d-ascorbic acid on the structure and properties of an epoxy matrix. Based on the test results, a modified epoxy matrix with improved adhesion and physicomechanical properties was developed. The nature of the chemical bonds in the structure of the synthesized modifier and its molar mass were investigated by gas chromatography. A significant number of hydroxyl groups in the structure of the d-ascorbic acid molecule is one of the main criteria that determine the activity of this nano modifying additive in terms of homogeneous interactions during the cross-linking of the epoxy binder-based compound. It has been established that modifying epoxy compositions with d-ascorbic acid in the amount of 0.75 to 1 mass % per 100 mass % of ED-20 epoxy resin ensures an increase in adhesion strength while reducing residual stresses. The positive impact of the modifier on improving the adhesive properties of the modified epoxy matrix to the metal substrate is due to the chemical structure of the nano modifying additive, which determines the intermolecular interaction in the homogeneous polymer system. It has been proven that the epoxy composite's cohesive property indicators (elastic modulus, destructive stresses, impact toughness) significantly increase at the optimal d-ascorbic acid content. This is due to the additional formation of physical and chemical bonds in the structural network of the compound during its cross-linking in the presence of the modifying additive, which affects the indicators of the material's cohesive strength and impact resistance. [ABSTRACT FROM AUTHOR]

Copyright of Dokuz Eylul University Muhendislik Faculty of Engineering Journal of Science & Engineering / Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi is the property of Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Radical cyclization cascade reactions of epoxycyclohexanes possessing alkene and alkyne side chains have been achieved. Sequential 5‐ or 6‐exo‐trig/5‐exo‐dig reactions triggered by epoxide ring opening with Cp2TiCl were found to provide a useful unified synthetic method for generating the carbon skeletons of clovane and cedrane, two tricyclic sesquiterpenes. The factors responsible for the development of stereoselectivity during cyclization are also discussed. [ABSTRACT FROM AUTHOR]

Herein we illustrate a first asymmetric synthesis of medicinally attractive tetrahydro‐1,4‐benzodiazepin‐2‐ones performed under catalytic conditions and one‐pot fashion. The process relies on a sequential Knoevenagel reaction/asymmetric epoxidation/domino ring‐opening cyclization (DROC) using commercially available aldehydes, phenylsulfonylacetonitrile, cumyl hydroperoxide, 2‐(aminomethyl)aniline and a readily available quinine‐derived urea as the catalyst. The heterocycles have been isolated with good regioselectivity, satisfactory to good yield and up to 98 % ee. The protocol proved also to be suitable for the preparation of previously undescribed 1,5‐dihydro‐4,1‐benzoxazepin‐3(2H)‐ones with up to 86 % ee. [ABSTRACT FROM AUTHOR]

Herein, we demonstrated an effective protocol for the regioselective ring opening of epoxides with alcohols. By following this strategy, both α‐alkylated ketones and β‐alkylated secondary alcohols were selectively obtained by changing the reaction parameters. Compared to the previously reported protocols, this methodology was operated using considerably lower base at lower temperature. Notably, a wide array of substrates with tolerance of different functional groups was demonstrated. A series of control experiments and deuterium‐labelling experiments were performed to understand this catalytic process. [ABSTRACT FROM AUTHOR]

A series of functional cross-linked polystyrenes was synthesized by the free radical copolymerization of divinylbenzene with functional styrenes and utilized as heterogeneous catalysts for the coupling of epoxides with CO2. Investigations showed that the cross-linked copolymer functionalized by quaternary ammonium chloride (CP1) exhibited high catalytic activity in the coupling reaction and thermostability at elevated temperatures. Thus, CP1 was easily recycled from the reaction mixture by filtration and reused without obvious loss of activity. Moreover, the activity of CP1 can be greatly enhanced by adding conventional Lewis acids such as anhydrous FeCl3 or AlCl3. Thus, copolymer 1/FeCl3 composites (1/1 molar ratio) transformed propylene oxide and CO2 to propylene carbonate in 92% yield in 10 h at 110 °C with the composite catalyst loading of 0.25 mol% with respect to propylene oxide and can be reused after simple filtration without significant decline of activity. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of carbon dioxide (CO2) for the preparation of higher carboxylic acids is attractive and promising. Herein, we demonstrate a general strategy for producing higher carboxylic acids via reaction of CO2 and H2 with light (C2~C4) oxygenates such as ketones, alcohols, polyols, ethers and epoxides. In a green solvent consisting of ionic liquid (1‐ethyl‐3‐methylimidazolium iodide) and water, the reaction can be efficiently accelerated by RhI3 catalyst and I2 promoter at 170 °C. Very high or remarkable yields of higher carboxylic acids were synthesized via C−C bond formation between the intermediates generated from the oxygenates and CO2. Detailed study indicated that the catalyst and the solvent had excellent synergistic effect for promoting the reaction. The strategy can effectively convert the bulk and inexpensive feedstocks to value‐added carboxylic acids, and therefore is promising for commercial application. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of carbon dioxide (CO2) for the preparation of higher carboxylic acids is attractive and promising. Herein, we demonstrate a general strategy for producing higher carboxylic acids via reaction of CO2 and H2 with light (C2~C4) oxygenates such as ketones, alcohols, polyols, ethers and epoxides. In a green solvent consisting of ionic liquid (1‐ethyl‐3‐methylimidazolium iodide) and water, the reaction can be efficiently accelerated by RhI3 catalyst and I2 promoter at 170 °C. Very high or remarkable yields of higher carboxylic acids were synthesized via C−C bond formation between the intermediates generated from the oxygenates and CO2. Detailed study indicated that the catalyst and the solvent had excellent synergistic effect for promoting the reaction. The strategy can effectively convert the bulk and inexpensive feedstocks to value‐added carboxylic acids, and therefore is promising for commercial application. [ABSTRACT FROM AUTHOR]

Chemoselective hydrogenation of α,β‐epoxy ketones and α‐ketoamides is achieved at room temperature (25 °C) using 2.0 bar H2 and a pincer‐ligated Mn(I) catalyst that provides synthetically valuable α‐hydroxy epoxides and α‐hydroxy amides. This protocol applies to a wide range of alkyl‐ and aryl‐substituted α,β‐epoxy ketones, including terpenes (α‐ionone, nootkatone, and R‐carvone)‐ and steroids (testosterone and progesterone)‐derived epoxy ketones, and tolerates H2 sensitive functionalities, such as halides, acetyl, nitrile, nitro, epoxide, alkenyl and alkynyl groups. Additionally, α‐ketoamides bearing reducible functional groups, including acetyl and diazo benzene, were untouched under this protocol and selectively converted to α‐hydroxy amides. A preliminary mechanistic study highlighted the metal‐ligand cooperative H2 activation process. [ABSTRACT FROM AUTHOR]

A novel CCOF core–shell composite material (S)-DTP-COF@SiO2 was prepared via asymmetric catalytic and in situ growth strategy. The prepared (S)-DTP-COF@SiO2 was utilized as separation medium for HPLC enantioseparation using normal-phase and reversed-phase chromatographic modes, which displays excellent chiral separation performance for alcohols, esters, ketones, and epoxides, etc. Compared with chiral commercial chromatographic columns (Chiralpak AD-H and Chiralcel OD-H columns) and some previously reported chiral CCOF@SiO2 (CC-MP CCTF@SiO2 and MDI-β-CD-modified COF@SiO2)-packed columns, there are 4, 3, 13, and 15 tested racemic compounds that could not be resolved on the Chiralpak AD-H column, Chiralcel OD-H column, CC-MP CCTF@SiO2 column, and MDI-β-CD-modified COF@SiO2 column, respectively, which indicates that the resolution effect of (S)-DTP-COF@SiO2-packed column can be complementary to the other ones. The effects of the analyte mass, column temperature, and mobile phase composition on the enantiomeric separation were investigated. The chiral column exhibits good reproducibility after multiple consecutive injections. The RSDs (n = 5) of the peak area and retention time were less than 1.5% for repetitive separation of 2-methoxy-2-phenylethanol and 1-phenyl-1-pentanol. The chiral core–shell composite (S)-DTP-COF@SiO2 exhibited good enantiomeric separation performance, which not only demonstrates its potential as a novel CSP material in HPLC but also expands the range of applications for chiral COFs. [ABSTRACT FROM AUTHOR]

Microelectronics packages play a vital role in not only interconnecting the electronic signals from the die to the printed circuit board (PCB), but also in protecting the chips during the manufacturing process and their subsequent service lives. Epoxy molding compound (EMC) is widely used in electronic packaging due to its superior processing capability and low circuit signal delay. However, interfacial delamination is a common problem in encapsulated silicon devices, particularly at the interface between the copper leadframe (LF) pads and the EMC due to the weaker adhesion strength. Accordingly, the present study employs a double cantilever beam (DCB) experimental testing method and a numerical model based on the virtual crack closure technique (VCCT) to investigate the fracture behavior at the EMC/Cu LF interface in a quad flat no leads (QFN) package. The experiments are performed on an MTS-Acumen microforce tester equipped with a load unit capable of applying a force of 0.01 to 1250 N with a displacement resolution of 0.1 μm. The DCB specimens are prepared with a pre-crack length of 12 mm. The validity of the simulation model is confirmed by comparing the predicted values of the critical strain energy release rate (SERR, Gc) between the EMC and the copper LF pads with the experimental observations. In general, the results show that the Gc value provides a useful parameter for evaluating the delamination risk of encapsulated microelectronics packages and assessing the reliability of alternative package architectures. [ABSTRACT FROM AUTHOR]

Background: Ethylene oxide, a reactive epoxy compound, has been widely used in various industries for many years. However, evidence of the combined toxic effects of ethylene oxide exposure on the liver is still lacking. Methods: We analyzed the merged data from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016. Ultimately, 4141 adults aged 18 and over were selected as the sample. We used linear regression to explore the association between blood ethylene oxide and LFT indicators. Results: The weighted linear regression model showed that HbEO is positively correlated with ALP (β = 2.61, 95% CI 1.97, 3.24, p < 0.0001), GGT (β = 5.75, 95% CI 4.46, 7/05, p < 0.0001), ALT (β = 0.50, 95% CI 0.09, 0.90, p = 0.0158), and AST (β = 0.71, 95% CI 0.44, 0.98, p < 0.0001) and negatively correlated with TBIL (β = −0.30, 95% CI −0.43, −0.16, p < 0.0001). Conclusions: Ethylene oxide exposure is significantly associated with changes in liver function indicators among adults in the United States. Future work should further examine these relationships. [ABSTRACT FROM AUTHOR]

Chiral epichlorohydrin (ECH) is an attractive intermediate for chiral pharmaceuticals and chemicals preparation. The asymmetric synthesis of chiral ECH using 1,3-dicholoro-2-propanol (1,3-DCP) catalyzed by a haloalcohol dehalogenase (HHDH) was considered as a feasible approach. However, the reverse ring opening reaction caused low optical purity of chiral ECH, thus severely restricts the industrial application of HHDHs. In the present study, a novel selective conformation adjustment strategy was developed with an engineered HheCPS to regulate the kinetic parameters of the forward and reverse reactions, based on site saturation mutation and molecular simulation analysis. The HheCPS mutant E85P was constructed with a markable change in the conformation of (S)-ECH in the substrate pocket and a slight impact on the interaction between 1,3-DCP and the enzyme, which resulted in the kinetic deceleration of the reverse reactions. Compared with HheCPS, the catalytic efficiency (kcat(S)-ECH/Km(S)-ECH) of the reversed reaction dropped to 0.23-fold (from 0.13 to 0.03 mM−1 s−1), while the catalytic efficiency (kcat(1,3-DCP)/Km(1,3-DCP)) of the forward reaction only reduced from 0.83 to 0.71 mM−1 s−1. With 40 mM 1,3-DCP as substrate, HheCPS E85P catalyzed the synthesis of (S)-ECH with the yield up to 55.35% and the e.e. increased from 92.54 to >99%. Our work provided an effective approach for understanding the stereoselective catalytic mechanism as well as the green manufacturing of chiral epoxides. [ABSTRACT FROM AUTHOR]

Reported herein is a stereoselective route to anti -β-hydroxy sulfoxides through the reaction of epoxides with sulfenate anions. Extensive experimental/computational studies revealed the dual special roles of MgBr2 ·OEt2 , serving to generate the bromohydrin alkoxide intermediate, which undergoes nucleophilic attack on the prochiral sulfenate in a diastereoselective manner. The present study has opened a general stereoselective synthetic route to anti -β-hydroxy sulfoxides. [ABSTRACT FROM AUTHOR]

Using carbon disulfide (CS2) and carbonyl sulfide (COS) as sulfur‐containing and one‐carbon feedstocks to make value‐added products is paramount for both pure and applied chemistry and environmental science. One of the practical strategies is to copolymerize these bulk chemicals with epoxides to produce sulfur‐containing polymers. This approach contributes to improving the sustainability of polymer manufacturing, provides highly desired functional polymer materials, and has attracted much attention. However, these copolymerizations invariably exhibit the intensely complicated chemistry of O/S exchange reaction, leading to sulfur‐containing polymers with diverse architectures. As the understanding of O/S exchange continues to deepen, recent efforts have guided significant advances in the synthesis of CS2‐ and COS‐based polymers. This review examines the O/S exchange chemistry and summarizes the recent progress in this field to promote the further advance of synthesizing sulfur‐containing polymers from CS2 and COS. [ABSTRACT FROM AUTHOR]

Borane catalysis has emerged as a powerful technology in epoxide polymerization. Still, the structure‐activity correlations for these catalysts are not fully understood to date, especially regarding compounds with nonionic backbones. Thus, in this work, 13 different borane catalysts of this respective type are described and investigated for their epoxide oligomerization and polymerization performance, using propylene oxide (PO), 1‐butylene oxide (BO) and allyl glycidyl ether (AGE) as monomers. Structurally, special emphasis is put on catalysts with different linker lengths and linker flexibilities as well as the introduction of more than two borane functionalities. Importantly, this screening is conducted both under typical polymerization conditions as well as under the chain transfer agent (CTA)‐rich conditions relevant for large‐scale production. It is found that suitable preorganization of the borane groups, such as present in biphenyl derivatives, offers a simple route to high‐performing catalysts and quantitative monomer conversion of the investigated epoxides. Furthermore, it is demonstrated that a diborane‐catalyzed oligomerization can be kept active over weeks, whereby repeated addition of monomer batches (14 steps) constantly results in full conversion and well‐defined oligoethers, underlining the practical potential of this method. The absence of co‐initiating counter ions is suggested as an inherent advantage of nonionic catalysts. [ABSTRACT FROM AUTHOR]

The alkylation of arenes is one of the most fundamental transformations in synthetic chemistry and the transition‐metal‐catalyzed direct C−H alkylation represents a straightforward and attractive approach from both atom and step‐economy perspectives. Epoxides, the smallest three‐membered saturated O‐heterocycles that can be easily prepared in racemic or enantioenriched forms, are highly useful building blocks for the synthesis of complex organic molecules. Owing to their inherent high ring‐strain, epoxides readily undergo ring‐opening reactions and have been used as alkylating reagents for C−H alkylation catalyzed by transition metals. This review summarizes recent advances in utilizing epoxides as alkylating reagents in transition‐metal‐catalyzed C−H alkylation as well as their synthetic applications in organic synthesis. [ABSTRACT FROM AUTHOR]

Transition metal‐catalyzed epoxidation of carbonyl compounds through carbonyl ylides represents a highly effective method for synthesizing a diverse range of valuable epoxides. This review offers an in‐depth overview of the latest developments in inter‐ and intramolecular epoxidation reactions involving metal carbenes and carbonyl compounds, encompassing both racemic to enantioselective transformations. These catalytic epoxidations are reviewed by highlighting their product selectivity, diversity and applicability, and the related mechanistic rationale is showcased where possible. [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]

Comprehensive Summary: The utilization of carbon dioxide (CO2) as a C1 feedstock is consistently attractive, especially in the preparation of sustainable polymeric materials. In this contribution, a terpolymer of CO2, 1,3‐butadiene (BD) and epoxide is synthesized by scandium triflate catalyzed cationic ring‐opening copolymerization of α‐ethylidene‐δ‐vinyl‐δ‐valerolactone (EVL), an intermediate derived from CO2 and BD, with epoxides. The obtained terpolymer with a CO2 content of 22 mol% has a number‐average molecular weight (Mn) up to 7.8 kg/mol and a dispersity (Đ) of 2.4. The reactivity ratios of EVL and cyclohexene oxide (CHO) are determined as 0.01 and 1.07, respectively, suggesting random characteristic of the terpolymer. The preserved C=C double bonds from BD allow for the further modification of the terpolymer by photoinitiated crosslinking. The yielded networks are fluorescent and degradable. This method offers enhanced versatility to the synthesis and additional functionalization of CO2‐based polymers. [ABSTRACT FROM AUTHOR]