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Dimethyl ether (DME) has promising properties as e‐fuel and platform chemical. Its direct synthesis from CO2 and hydrogen, which is thermodynamically more favorable than the indirect route over methanol, is reviewed. Systematic thermodynamic equilibrium calculations are evaluated and compared to bifunctional catalysis experiments performed with Cu/ZnO/ZrO2 methanol catalyst and ferrierite or heteropolyacid‐coated dehydration catalysts under thermodynamic and kinetic conditions. In the thermodynamic region, the methyl yield of direct DME synthesis is superior over sole methanol synthesis. Significant differences among the solid acids used are absent. However, under kinetic conditions, the heteropolyacid‐coated catalysts show superior performance for dehydration over zeolites. [ABSTRACT FROM AUTHOR]

Peroxisomes are highly plastic organelles that are involved in several metabolic processes, including fatty acid oxidation, ether lipid synthesis and redox homeostasis. Their abundance and activity are dynamically regulated in response to nutrient availability and cellular stress. Damaged or superfluous peroxisomes are removed mainly by pexophagy, the selective autophagy of peroxisomes induced by ubiquitylation of peroxisomal membrane proteins or ubiquitin-independent processes. Dysregulated pexophagy impairs peroxisome homeostasis and has been linked to the development of various human diseases. Despite many recent insights into mammalian pexophagy, our understanding of this process is still limited compared to our understanding of pexophagy in yeast. In this Cell Science at a Glance article and the accompanying poster, we summarize current knowledge on the control of mammalian pexophagy and highlight which aspects require further attention. We also discuss the role of ubiquitylation in pexophagy and describe the ubiquitin machinery involved in regulating signals for the recruitment of phagophores to peroxisomes. [ABSTRACT FROM AUTHOR]

A photochemical synthesis of enol ethers and furan-3(2H)-ones from 1,3-dicarbonyl compounds and aryl diazoacetates has been developed. Significantly, 1,4-dioxane promoted O-alkylation of various 1,3-dicarbonyl compounds beyond previous carbene insertion into C–H and C–C bonds has been disclosed. [ABSTRACT FROM AUTHOR]

We have accomplished the first and asymmetric total synthesis of principinol B, a grayanoid possessing an oxabicyclo[3.2.1] architecture. A functionalized 5/7/6/5 tetracyclic intermediate was assembled in a convergent manner by a diastereoselective intermolecular aldol reaction and subsequent carbonyl–olefin metathesis of two enantiomerically enriched fragments. The oxabicyclo[3.2.1] architecture containing a 6,10‐ether bridge was constructed by the Williamson ether synthesis. [ABSTRACT FROM AUTHOR]

We have accomplished the first and asymmetric total synthesis of principinol B, a grayanoid possessing an oxabicyclo[3.2.1] architecture. A functionalized 5/7/6/5 tetracyclic intermediate was assembled in a convergent manner by a diastereoselective intermolecular aldol reaction and subsequent carbonyl–olefin metathesis of two enantiomerically enriched fragments. The oxabicyclo[3.2.1] architecture containing a 6,10‐ether bridge was constructed by the Williamson ether synthesis. [ABSTRACT FROM AUTHOR]

An alternate synthetic approach was developed for the synthesis of the digeranyl ether and naturally occurring biologically active geranyl phenols using −SO3H functionalized ionic liquids within 0.5–1.5 h with better yields. This approach was further explored for different naturally occurring activated phenols with geraniol yielding geranyl phenols via alkylation at ambient temperature using ionic liquids as catalyst. The synthesized ionic liquids were characterized using Py‐IR studies to establish the Brønsted acidity and the Hammett acidity characteristics of all the four ionic liquids. Amongst these ionic liquids IL‐1 exhibited beneficial catalytic activity towards the synthesis of digeranyl ether and geranyl phenols with excellent yields. Reusability studies indicated that IL‐1 was recycled for seven times without losing the catalytic activity which was further corroborated with pre‐ and post‐characterization of IL‐1. This work also highlights the alternate route for the synthesis of the cannabinoid compounds and their analogues. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed regioselective hydroarylation of terminal alkynes containing a heteroatom has been developed via carbopalladation for the synthesis of allylic ethers, amines, and homoallylic alcohols. Moreover, hydroalkenylation of alkynes produces a variety of stereodefined 1,4-dienes with high regioselectivity. The important features of the present protocol are that it is highly regioselective, operationally rapid, and scalable with a huge substrate scope using only 3 mol% of PdCl2(PPh3)2 catalyst in the presence of a mild base KOAc. [ABSTRACT FROM AUTHOR]

In this research, some new eighteen‐membered‐ring nitrogen‐pivot lariat ethers were synthesized from a tri‐aza macrocyclic diamide containing dibenzosulfide and a coumarin fragment as the sidearm. The aza‐macrocyclic compound used in the synthesis of lariat ethers was obtained from the reaction of dibenzosulfide diester and diethylenetriamine. The corresponding 3‐amidocoumarins were synthesized from the reaction of 3‐aminocoumarins and chloroacetyl chloride in good yields. Moreover, symmetrical bis coumarin podands were prepared by reacting a sulfide or sulfoxide monomer with 3‐amidocoumarin. The structures of the products were identified by IR, 1H NMR, 13C NMR, and mass spectroscopies. [ABSTRACT FROM AUTHOR]

Cellulose derivatives have attracted attention as environmentally friendly materials that can exhibit a cholesteric liquid crystal (CLC) phase with visible light reflection. Previous reports have shown that the chemical structures and the degrees of substitution of cellulose derivatives have significant influence on their reflection properties. Although many studies have been reported on CLC using ethyl cellulose (EC) derivatives in which the hydroxy groups are esterified, there have been no studies on EC derivatives with etherified side chains. In this article, we optimized the Williamson ether synthesis to introduce pentyl ether groups in the EC side chain. The degree of substitution with pentyl ether group (DSPe), confirmed via 1H-NMR spectroscopic measurements, was controlled using the solvent and the base concentration in this synthesis. All the etherified EC derivatives were soluble in methacrylic acid (MAA), allowing for the preparation of lyotropic CLCs with visible reflection. Although the reflection peak of lyotropic CLCs generally varies with temperature, the reflection peak of lyotropic CLCs of completely etherified EC derivatives with MAA could almost be preserved in the temperature range from 30 to 110 °C even without the aid of any crosslinking. Such thermal stability of the reflection peak of CLCs may be greatly advantageous for fabricating new photonic devices with eco-friendliness. [ABSTRACT FROM AUTHOR]

We have developed a simple and direct method for the synthesis of diaryl ether under mild reaction conditions using an oxygen bridged bimetallic CuMoO4 nanocatalyst. The catalyst tolerated a wide range of substrates with various functional groups. The catalyst is efficient and recyclable. This methodology allowed easy access to nitrofen derivatives (herbicides) from unactivated 2,4-dichlorophenol, which are important for agriculture and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Vinyl ethers are valuable synthetic intermediates which are also found as natural products, including aflatoxins, rifamycins and plasmalogens. The latter are ubiquitous phospholipids in human cells and contain a vinyl ether moiety with specifically Z configuration. Although numerous methods are available for synthesis of vinyl ethers, there is a lack of methods for obtaining Z isomers of molecules of the type RCH=CHOR' that are applicable to plasmalogens. A variant of the Peterson reaction is described that generates such molecules with very high stereoselectivity (Z/E ratio: 99 : 1). (R,R)/(S,S)‐1‐alkoxy‐2‐hydroxyalkylsilanes were synthesized from 1‐trimethylsilylalkynes by a sequence of reduction with di‐isobutylaluminium hydride to a (Z)‐1‐trimethylsilylalkene, epoxidation of the alkene to a 2‐trimethylsilyl‐3‐substituted epoxide and regioselective, boron‐trifluoride catalyzed ring‐opening of the epoxide by reaction with an alcohol. Conversion of the (R,R)/(S,S)‐1‐alkoxy‐2‐hydroxyalkylsilanes to vinyl ethers (RCH=CHOR') was achieved under basic conditions as in a standard Peterson reaction. However, near exclusive formation of a Z vinyl ether was only achieved when the reaction was performed using potassium hydride in the non‐polar solvent α,α,α‐trifluorotoluene, more polar solvents giving increasing amounts of the E isomer. The sequence described embraces a variety of substituents and precursors, proceeds in overall high yield and is readily scalable. [ABSTRACT FROM AUTHOR]

This study describes an efficient approach to access oxime ethers via P(III)-mediated O–H bond insertion reaction of oximes with α-keto esters. The strategy involves the protonation of in situ generated Kukhtin–Ramirez adducts, followed by SN2-type reaction. Important features include a good functional group tolerance, operational simplicity, and application to gram scale synthesis and the synthesis of an acaricide. [ABSTRACT FROM AUTHOR]

The asymmetric synthesis of polyunsaturated triene C18:3 n-3 and C18:3 n-6 methoxylated ether lipids (MEL) of the 1-O-alkyl-sn-glycerol type is described as possible structural candidates for a triene C18:3 MEL of an unknown identity found in a mixture of shark and dogfish liver oil. Their C18:3 hydrocarbon chains constitute an all-cis methylene skipped n-3 or n-6 triene framework, along with a methoxyl group at the 2′-position and R-configuration of the resulting stereogenic center. The methoxylated polyenes are attached by an ether linkage to the pro-S hydroxymethyl group of the glycerol backbone. The syntheses were based on the polyacetylene approach that involves a semi-hydrogenation of the resulting triynes. Both syntheses were started from our previously described enantio- and diastereomerically pure isopropylidene-protected glyceryl glycidyl ether, a double-C3 building block that was designed as a head group synthon for the synthesis of various types of MELs. [ABSTRACT FROM AUTHOR]

The β‐adrenergic receptor blocking agents are an important class of drug molecules. The present study reports a new chemo and chemo‐enzymatic synthetic process for (RS)‐, (R)‐, and (S)‐bunolol, one of the potent β‐adrenergic receptor blocker. In chemo‐enzymatic process, CAL L4777 lipase was employed for enantioselective kinetic resolution to synthesize the enantiopure (R)‐alcohol and (S)‐ester from the corresponding racemic alcohol. Thereafter, the corresponding (R)‐alcohol and deacylated (S)‐ester were treated with tert‐butylamine to produce (S)‐ and (R)‐bunolol, respectively. In chemical approach, epichlorohydrin (RS‐, R‐, and S‐) was used as a starting material via respective (RS)‐, (S)‐, and (R)‐glycidyl ether as intermediates for synthesis of enantiomeric (RS)‐, (R)‐, and (S)‐bunolol. In comparison between two approaches, it was found that the chemo‐enzymatic process was more effective and resulted in enantiomeric excess of 98% with 35% yield. [ABSTRACT FROM AUTHOR]

Methanol is one of the most abundant interstellar Complex Organic Molecules (iCOMs) and represents a major building block for the synthesis of increasingly complex oxygen-containing molecules. The reaction between protonated methanol and its neutral counterpart, giving protonated dimethyl ether, $ \require{mhchem} \ce{(CH3)2OH+} $ (CH 3 ) 2 OH + , along with the ejection of a water molecule, has been proposed as a key reaction in the synthesis of dimethyl ether in space. Here, gas phase vibrational spectra of the $ \ce{(CH3)2OH+} $ (CH 3 ) 2 OH + reaction product and the $ \ce{[C2H9O2]+} $ [ C 2 H 9 O 2 ] + intermediate complex(es), formed under different pressure and temperature conditions, are presented. The widely tunable free electron laser for infrared experiments, FELIX, was employed to record these vibrational fingerprint spectra using different types of infrared action spectroscopy in the 600-1700 cm $ ^{-1} $ − 1 frequency range, complemented with measurements using an OPO/OPA system to cover the $ \ce{O-H} $ O − H stretching region $ 3400-3700\,{\rm cm}^{-1} $ 3400 − 3700 c m − 1 . The formation of protonated dimethyl ether as a product of the reaction is spectroscopically confirmed, providing the first gas-phase vibrational spectrum of this potentially relevant astrochemical ion. [ABSTRACT FROM AUTHOR]

An expedient synthesis of silyl ethers is reported via photocatalytic free radical coupling of ketones with hydrosilanes and subsequent [1, 2]‐Brook rearrangement. This strategy features the advantages of 100 % atom economy, environmental friendliness, easily available starting materials as well as late‐stage functionalization of complex molecules. [ABSTRACT FROM AUTHOR]

This research was designed to isolate pinostrobin from Kaempferia pandurata Roxb. rhizome using a chromatography method and to study its structural modification through ethylation and allylation reactions. Two compounds were afforded from the ethylation reaction that were 5-ethoxy-7-methoxyflavanone and 4′-ethoxy-6′-methoxychalcone and in the case of the allylation, 5-O-allylpinostrobin (5-allyloxy-7-methoxyflavanone) and 6-allylpinostrobin (6-allyl-5-hydroxy-7-methoxyflavanone) were obtained. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) hydrogenation is an alternative catalytic reaction for the conversion of CO2 into methanol and dimethyl ether (DME). Alumina is widely used as a catalyst in CO2 hydrogenation. Drying of the porous support is an effective process, which can directly affect the structural characteristics and performance of the catalyst. This work investigated the effect of microwave drying on the properties of an alumina support and a Cu/Al2O3 catalyst. Microwave drying of the support at 600 and 1000 W shortened the drying time by 86 and 92%, respectively, compared to hot air drying at 100 °C. Microwave drying could enhance the distribution of the alumina particles, resulting in a larger surface area and pore volume of the support. In contrast, hot air drying caused alumina particle aggregation that led to a small surface area and pore volume of the support. The Cu/Al2O3 catalyst, for which the support was microwave-dried at 1000 W (Cu/Al2O3-MW1000), had the greatest copper distribution, BET surface area (229.5 m2/g), pore volume (0.39 m3/g) and strong acidic site (1.25 mmol NH3/g Cu). These characteristics of catalyst led to the presenting of the highest CO2 conversion, DME selectivity, and DME space time yield during CO2 hydrogenation. A catalyst utilizing the support prepared by microwave drying at 1000 W exhibited the highest average CO2 conversion, DME selectivity and space time yield of DME of 30.67%, 9.99% and 156.5 gDME/kgcat h, respectively at a reaction temperature of 260 °C for 4 h. In addition, the stability of Cu/Al2O3-MW1000 catalyst was excellent over a 24 h reaction period. [ABSTRACT FROM AUTHOR]

A visible light-induced kinetic controlled regioselective O-alkylation of various 1,3-dicarbonyl compounds with diazoacetates and cyclic ethers has been developed. The protocol provides a green and practical approach to highly stereoselective enol ethers under mild and base-free conditions in good to excellent yields. [ABSTRACT FROM AUTHOR]

In this study, glycerol derivatives, namely solketal ethers (SEs), were synthesized by Williamson etherification of solketal with alkyl bromide, catalyzed by tetrabutylammonium iodide (TBAI) and basic aqueous potassium hydroxide (KOH). Under optimized reaction conditions: solketal/alkyl bromide (1 : 1), TBAI (5 mol %), KOH solution (2 equiv), 100 °C, 24 hours, SE were obtained between 21 and 94 %. The influence of the incorporation of SE in palm‐based biodiesel was evaluated using kinematic viscosity, cloud point (CP), and pour point (PP). The addition of 5 wt % of 4‐((butoxy)methyl)‐2,2‐dimethyl‐1,3‐dioxolane reduced PP and CP by 5 and 3 °C, respectively, with viscosity values well within the range of ASTM D6751‐12 standard specifications. [ABSTRACT FROM AUTHOR]

Polyethers and polythioethers have a long and storied history dating back to the start of polymer science as a distinct field. As such, these materials have been utilized in a wide range of commercial applications and fundamental studies. The breadth of their material properties and the contexts in which they are applied is ultimately owed to their diverse monomer pre-cursors, epoxides and thiiranes, respectively. The facile polymerization of these monomers, both historically and contemporaneously, across academia and industry, has occurred through the use of Earth-abundant metals as catalysts and/or initiators. Despite this, polymerization methods for these monomers are underutilized compared to other monomer classes like cyclic olefins, vinyls, and (meth)acrylates. We feel a focused review that clearly outlines the benefits and shortcomings of extant synthetic methods for poly(thio)ethers along with their proposed mechanisms and quirks will help facilitate the utilization of these methods and by extension the unique polymer materials they create. Therefore, this Feature Article briefly describes the applications of poly(thio)ethers before discussing the feature-set of each poly(thio)ether synthetic method and qualitatively scoring them on relevant metrics (e.g., ease-of-use, molecular weight control, etc.) to help would-be poly(thio)ether-makers find an appropriate synthetic approach. The article is concluded with a look ahead at the future of poly(thio)ether synthesis with Earth-abundant metals. [ABSTRACT FROM AUTHOR]

Three new thiadiamidocrown ethers 1-3 have been synthesized and characterized by 1H-NMR, 13C-NMR and mass spectrometry. A thermodynamic study of the complexation of compounds 1-5 with metal cations (Mn+); Pb2+ with 1, 2, 4, and 5; Ag+ with 1, 2, and 3 and Hg2+ with 2 in acetonitrile, has been carried out at 288-308 K using a conductometric technique. The observed molar conductivity of the metal salts solutions, ⋀, was found to decrease upon addition of crown ethers solutions and tend to level off near the mole ratios [L]T/[M]T of unity. The ΔH° and ΔS° values for the complexation reactions were evaluated from the slopes and intercepts of the van't Hoff plots, respectively. The results show that the stability constants of Pb2+ complexes at 25 °C vary as: 5 > 4 > 2 > 1 while the stability constants of Ag+ complexes vary as: 3 > 2 > 1. ΔG° values for all complexes have negative values indicating a spontaneous complex formation process. A theoretical calculations using DFT which was conducted on the above systems gave results that supported the experimental results in most of the cases. [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]

Reductive etherification is an attractive and practical strategy to convert bio-platform compounds into valuable chemicals. In directed synthesis of furfuryl ethers, reductive etherification of bioderived furfurals is still challenging due to the complexity of catalytic reaction. Herein, reductive etherification of furfural with alcohol was investigated over Ni/ZSM-5 catalyst, which found that Si/Al ratios in ZSM-5 played an important role on the catalytic performance. For Ni/ZSM-5 with Si/Al ratio of 50, 80.9% yield of furfuryl ether at 90.8% conversion of furfural was achieved under the condition of 2 MPa H 2 and 180 °C for 3 h in isopropanol. The catalyst exhibited superior stability and recyclability during the consecutive cycle run. Catalysts characterization demonstrated that both acidic properties and furfural adsorption were influenced by the Si/Al ratios in Ni/ZSM-5, which correlated to the reaction route and catalytic performance. Lewis acid sites enhanced furfural hydrogenation into furfuryl alcohol, while Brønsted acid sites on ZSM-5 effectively catalyzed sequential etherification of furfuryl alcohol to furfuryl ether. Under optimization conditions, various furfuryl ethers could be obtained with yields above 80% over Ni/ZSM-5 catalyst in different primary alcohols, demonstrating the general versatility of the approach. Our findings offered opportunities to develop an efficient furfuryl ethers synthesis method. A synergistic effect between Lewis and Brønsted acid sites in Ni/ZSM-5 accelerated the reductive etherification of furfural and alcohols. [Display omitted] [ABSTRACT FROM AUTHOR]

A new benzyl-type protecting group (1,4-dimethoxynaphthalene-2-methyl, 'DIMON') for hydroxyl functions can be selectively removed under oxidative conditions without damaging polyunsaturated fatty acyl groups. Its application is shown by the first synthesis of an ether (plasmanyl) phospholipid containing the docosa-(4Z,7Z,10Z,13Z,16Z,19Z)-hexaenoyl group. [ABSTRACT FROM AUTHOR]

Alkoxylation of benzylic C(sp3)−H bonds has become one of the most important tools for the construction of benzyl ethers from feedstock chemicals. Herein, we reported a silver catalyzed alkoxylation of benzylic C(sp3)−H bonds employing potassium persulfate as an oxidant at room temperature. This strategy showed good functional‐group tolerance, site selectivity, and chemoselectivity. The reaction proceeded smoothly in the presence of various primary, secondary, and tertiary alcohol nucleophiles, affording corresponding benzyl ethers. Combined experimental studies provided mechanistic insights into the possible radical pathways. Furthermore, a possible mechanism was proposed for this method. [ABSTRACT FROM AUTHOR]

In this study 4 different acid catalysts were prepared and mixed with commercial CZA catalysts and investigated in direct DME synthesis. Some of the used acid catalysts were not investigated in the literature therefore the work involves novelty. In a fixed-bed reactor, dimethyl ether (DME) was synthesized from the synthesis gas on two catalysts from, natural clinoptilolite and zeolite catalysts. The clinoptilolite (HK and DK) and two (HZSM5(117) and HZSM5(360)) catalysts mixed with commercial CuO/ZnO/Al 2 O 3 (CZN) catalysts. The catalysts were also characterized by analytical chemistry techniques such as XRD, BET, TGA, and FTIR. Four different catalysts (HK, DK, HZSM5(117) and HZSM5(360)) and CZA catalysts were mixed at a ratio of 3/1, respectively, and studies were carried out in a fixed-bed reactor. Four different catalyst composition activity tests were made at temperatures 250, 275, and 300 °C. At the same time, the pressure was 30 and 40 bar and four different times (30, 60, 90, and 120 min). The composition of the gases fed to the system for DME was adjusted to N 2 /CO 2 /CO/H 2 = 36/10/18/36 by volume. DME selectivity (S DME) and total carbon (X C) conversion were calculated for each condition. The experimental results showed that the highest DME selectivity of 96.50% was observed in the reaction of the DK + CZA catalyst mixture at 250 °C and 30 min at 40 bar. In addition, high DME selectivity was obtained in all reactions of DK + CZA and HK + CZA catalyst compositions at three different temperatures. The highest DME selectivity obtained is 89.69% for the reaction of the HK + CZA catalyst mixture at 300 °C and 60 min at 30 bar. Experimental results gave insights into Dimethyl ether synthesis from syngas on clinoptilolite zeolite and HZSM5-based hybrid catalysts in a fixed-bed reactor. • Dimethyl ether was synthesized from the synthesis gas on clinoptilolite and zeolite catalysts in a fixed-bed reactor. • Experimental results gave valuable insights on Dimethyl ether synthesis from syngas on clinoptilolite zeolite. • The clinoptilolite based catalysts and H-ZSM5(117) and H-ZSM5(360) catalysts mixed with commercial CuO/ZnO/Al2O3 catalysts. • The highest DME selectivity of 96.50% was obtained in the reaction of the DK + CZA catalyst mixture at 250 °C and 30 min. • The highest DME selectivity was 89.69% for the reaction of the HK + CZA catalyst mixture at 300 °C and 60 min and 30 bar. [ABSTRACT FROM AUTHOR]

Tandem reactions, with their great potential for reduction of capital and operational costs, reaction time, and byproducts are becoming more prominent. Among possible tandem reaction systems for direct conversion of CO2 to green fuel, dimethyl ether synthesis via methanol route is of vital importance. However, there are several parameters which must be considered for the combination of two catalysts to achieve promising performance, of those, the distance between the two catalysts is a crucial one. This distance can affect the overall performance of the tandem system by causing external mass transfer limitations or the poisoning of the catalysts. This work presents a systematic study on the influence of the distance between the two catalysts for the CO2 to dimethyl ether tandem system. [ABSTRACT FROM AUTHOR]

The asymmetric synthesis of a triene C18 : 3 n‐8 methoxylated ether lipid (MEL) of the 1‐O‐alkyl‐sn‐glycerol type is described by two different routes. The C18 : 3 hydrocarbon chain is attached by an ether linkage to the pro‐S hydroxymethyl group of the glycerol backbone, and constitutes an all‐cis methylene skipped triene framework, along with a methoxyl group in the 2'‐position and R‐configuration at the resulting chiral centre. The initial synthesis was based on the polyacetylene approach involving a semi‐hydrogenation of the resulting triyne. A modified approach based on a combined polyacetylene‐Wittig strategy was also successfully executed and an attempt made to compare and evaluate these strategies. Both syntheses were started from our previously described enantio‐ and diastereomerically pure isopropylidene‐protected glyceryl glycidyl ether, a double‐C3 building block designed as a head group synthon for synthesis of various types of MELs which was shown to suit the Wittig‐based approach very well. [ABSTRACT FROM AUTHOR]

Converting CO2 into chemicals, e.g., methanol and dimethyl ether (DME), has been an attractive way to protect the global environment. In this process, the total catalyst volume of the methanol reactor was split into two sections to load the reactors. The catalyst volume of each reactor was optimized by the differential evolution technique. It was concluded that the indirect route yields a higher DME production rate than the direct one, as it produces higher amounts of methanol. CO2 conversions increased by 79 % in the indirect two‐stage process, which resulted in the highest DME production rate of 343 t per day. The results demonstrate how the concept of a two‐stage process in the indirect conversion of CO2 is feasible and beneficial for fuel production. [ABSTRACT FROM AUTHOR]

A facile one-step synthetic approach to dihydrofuro-[3,2- c ]chromenones and furo[3,2- c ]chromenones by the reaction of methyl enol ethers with 4-hydroxycoumarins under metal-free conditions is presented. Dihydrofuro[3,2- c ]chromenones and furo[3,2- c ]-chromenones were selectively obtained by controlling the stoichiometry of boron trifluoride diethyl etherate. An unexpected aryl-group migration followed by aromatization of the furan moiety, leading to a variety of furo[3,2- c ]chromenone derivatives in good yields, is reported. [ABSTRACT FROM AUTHOR]

The strained/frustrated electrostatic interactions between the ion pair of TTBPy+ X– increases the reactivity in both the ions, resulting in the activation of a third molecule like sulfonamides (aromatic/-aliphatic) via hydrogen bonding. This intriguing weak-interactions-based reactivity has been utilized to develop an organocatalytic synthesis of 2-deoxy-sulfonamido-glycosides from glycals. The sulfonamidoglycosylation of glycals using a catalytic amount of 2,4,6-tri- tert -butylpyridinium salts proceeded stereoselectively to provide N -glycosides in good to high yields. This process was demonstrated with l -rhamnal and d -galactal. Besides, IR spectroscopic studies explain that the hindered protonated pyridine cannot behave as a cationic Brønsted acid as is generally perceived. [ABSTRACT FROM AUTHOR]

Sugar-fatty acid esters (SFAEs, especially sucrose- and glucose-based ones) have dominated the chemical industries for more than 50 years. In comparison to other carbohydrate products, SFAEs serve essential roles in a variety of industries, including the food, pharmaceutical, and cosmetic industries. In this context, the 6-O-hexanoyl ester of 3-O-butyl-1,2-O-isopropylidene-a-D-glucofuranose was synthesized from commercially available Dglucose in a few steps. For a comparative biological study, the 5,6-di-O-benzyl ether of 3-O-butyl-1,2-Oisopropylidene-a-D-glucofuranose was also prepared and characterized. An in vitro antimicrobial test of all the ester and ether compounds indicated that these compounds are more susceptible to fungi than bacteria. Also, they have more potential for A. niger than A. flavus. According to Prediction of Spectra for Substances (PASS), the chemicals found in the current investigation have a variety of potential biological functions. [ABSTRACT FROM AUTHOR]

Axially chiral diaryl ethers are a type of unique atropisomers bearing two potential axes, which have potential applications in a variety of research fields. However, the catalytic enantioselective synthesis of these diaryl ether atropisomers is largely underexplored when compared to the catalytic asymmetric synthesis of biaryl or other types of atropisomers. Herein, we report a highly efficient catalytic asymmetric synthesis of diaryl ether atropisomers through an organocatalyzed enantioselective desymmetrization protocol. The chiral phosphoric acid‐catalyzed asymmetric electrophilic aromatic aminations of the symmetrical 1,3‐benzenediamine type substrates afforded a series of diaryl ether atropisomers in excellent yields and enantioselectivities. The facile construction of heterocycles by the utilizations of the 1,2‐benzenediamine moiety in the products provided access to a variety of structurally diverse and novel azaarene‐containing diaryl ether atropisomers. [ABSTRACT FROM AUTHOR]

Axially chiral diaryl ethers are a type of unique atropisomers bearing two potential axes, which have potential applications in a variety of research fields. However, the catalytic enantioselective synthesis of these diaryl ether atropisomers is largely underexplored when compared to the catalytic asymmetric synthesis of biaryl or other types of atropisomers. Herein, we report a highly efficient catalytic asymmetric synthesis of diaryl ether atropisomers through an organocatalyzed enantioselective desymmetrization protocol. The chiral phosphoric acid‐catalyzed asymmetric electrophilic aromatic aminations of the symmetrical 1,3‐benzenediamine type substrates afforded a series of diaryl ether atropisomers in excellent yields and enantioselectivities. The facile construction of heterocycles by the utilizations of the 1,2‐benzenediamine moiety in the products provided access to a variety of structurally diverse and novel azaarene‐containing diaryl ether atropisomers. [ABSTRACT FROM AUTHOR]

Tetrahydrofuran rings are present in a wide variety of biologically active molecules, which highlights the importance of developing a mild, convenient method for synthesizing compounds bearing these rings. Herein, we report an electrochemical protocol for phosphorous acid-assisted synthesis of hemiaminal ethers by means of α-C(sp³)-H/N-H cross-coupling reactions between tetrahydrofuran and sulfonamides or amides. This protocol does not require a chemical oxidant and can be performed at room temperature. Various sulfonamides and amides were suitable substrates, giving moderate to high yields of the desired cross-coupling products. [ABSTRACT FROM AUTHOR]

In this work, we propose two bifunctional nanocomposite catalysts based on acidic mesostructured γ-Al2O3 and a Cu/ZnO/ZrO2 redox phase. γ-Al2O3 was synthesized by an Evaporation-Induced Self-Assembly (EISA) method using two different templating agents (block copolymers Pluronic P123 and F127) and subsequently functionalized with the redox phase using an impregnation method modified with a self-combustion reaction. These nanocomposite catalysts and their corresponding mesostructured supports were characterized in terms of structural, textural, and morphological features as well as their acidic properties. The bifunctional catalysts were tested for the CO2-to-DME process, and their performances were compared with a physical mixture consisting of the most promising support as a dehydration catalyst together with the most common Cu-based commercial redox catalyst (CZA). The results highlight that the most appropriate Pluronic for the synthesis of γ-Al2O3 is P123; the use of this templating agent allows us to obtain a mesostructure with a smaller pore size and a higher number of acid sites. Furthermore, the corresponding composite catalyst shows a better dispersion of the redox phase and, consequently, a higher CO2 conversion. However, the incorporation of the redox phase into the porous structure of the acidic support (chemical mixing), favoring an intimate contact between the two phases, has detrimental effects on the dehydration performances due to the coverage of the acid sites with the redox nanophase. On the other hand, the strategy involving the physical mixing of the two phases, distinctly preserving the two catalytic functions, assures better performances. [ABSTRACT FROM AUTHOR]

Directly synthesising dimethyl ether (DME) from CO2 hydrogenation is a promising technique for efficiently utilising CO2 as a feedstock to produce clean fuel. The main challenges in this process are the low CO2 conversion and DME selectivity of the catalyst and its deactivation over time due to sintering, aggregation, coke formation, and water adsorption. This study aimed to develop a dual-functional, halloysite nanotube-supported CuZnO-PTA catalyst with a core-shell structure and investigate the effects of the active site mass ratio CuZnO/PTA on CO2 conversion and DME selectivity. A dual-functional core-shell mesopores halloysite nanotube (HNT) catalyst was developed, and both active sites were co-hosted on one support. The co-impregnation method was used to synthesise CuZnO and 12-phosphotungstic acids (PTA) that were then supported by a mesoporous core-shell (HNT). BET surface area, N2 physisorption, FE-SEM, SEM, XRD, H2-TPR, and NH3-TPD of the core-shell catalyst characterised physio-chemical properties of the prepared hybrid catalyst. The experimental results showed that the synthesised CuZn-PTA@HNT core-shell bifunctional catalyst was promising; the CO2 conversion was almost the same for all four catalysts, with an average of 22.17%, while the DME selectivity reached 68.9%. Furthermore, the effect of both active sites on the hybrid catalyst was studied, and the metal Cu wt% mass ratio loading was not significant. In contrast, the PTA acid sites positively affected DME selectivity; they also showed an excellent tolerance towards the water generated in the methanol dehydration reaction. In addition, the effect of the temperature and reusability of the CZ-PTA@HNT catalyst has also been investigated, and the results show that increasing the temperature improves CO2 conversion but decreases DME selectivity. A temperature of less than 305 °C is a good compromise between CO2 conversion and DME selectivity, and the catalyst also showed good stability and continuous activity/stability over five consecutive cycles. In conclusion, this study presents a novel approach of using a core-shell halloysite nanotube-supported CuZnO-PTA catalyst to directly synthesise dimethyl ether (DME) from CO2 hydrogenation which exhibits promising results in terms of CO2 conversion and DME selectivity. [ABSTRACT FROM AUTHOR]

In this study, macro-ringed benzo-aza-oxa-crown ethers were synthesized by a cyclization reaction between 2,2′-dithiodianiline and mono/di/tri/tetraethylene glycol dichloride/dibromide with Cs2CO3 as a catalyst under nitrogen atmosphere by the SN2 mechanism using the microwave synthesis method, which is one of the green chemistry methods. Structural characterizations of the original 2,2′-dithiodibenzo crown ether derivatives were confirmed with melting point, FT-IR, 1H NMR, 13C NMR, LC-MS/MS, elemental analysis, UV and fluorescence spectroscopy methods. In addition, the inhibition effects of these synthesized four crown ethers on human erythrocyte carbonic anhydrase (hCA I–II) isoenzyme activities were investigated. The synthesized compounds include aromatic benzene rings, nitrogen, sulfur, and oxygen donor atoms. The effects of aromaticity, S,S′-disulfide bond, nitrogen and oxygen donor atoms on the activity of carbonic anhydrase isoenzyme have been studied. (1,8,11,18)-Tetraaza[2,3-6,7-12,13-16,17]tetrabenzo-(4,5,14,15)-tetrathiocycloeicosane showed the highest inhibition effect on hCA I (Ki = 0.353±0.154 µM) and hCA II (Ki = 1.588±0.998 µM) enzyme. [ABSTRACT FROM AUTHOR]

A visible light-induced carbene reactivity of acceptor diazoalkanes has been developed for the synthesis of difunctionalized ethers from cyclic ethers and various N/O/S nucleophiles. [ABSTRACT FROM AUTHOR]

Estradiol (E2) plays an important role in the progression of diseases such as breast cancer and endometriosis. Inhibition of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1), the enzyme that catalyzes the last step in the biosynthesis of the estrogenic hormone E2, therefore constitutes an interesting approach for the treatment of these two estrogen-dependent diseases. In order to obtain new inhibitors of 17β-HSD1, the impact of a m-carbamoylphenyloxy group at position three of an estrane nucleus was evaluated by preparing three derivatives of estrone (E1) and E2 using a microwave-assisted synthesis of diaryl ethers. Their inhibitory activity was addressed on two cell lines (T-47D and Z-12) representative of breast cancer and endometriosis, respectively, but unlike T-47D cells, Z-12 cells were not found suitable for testing potential 17β-HSD1 inhibitors. Thus, the addition of the m-carbamoylphenyl group at C3 of E1 (compound 5) did not increase the inhibition of E1 to E2 transformation by 17β-HSD1 present in T-47D cells (IC50 = 0.31 and 0.21 μM for 5 and E1, respectively), and this negative effect was more obvious for E2 derivatives 6 and 10 (IC50 = 1.2 and 1.3 μM, respectively). Molecular docking allowed us to identify key interactions with 17β-HSD1 and to highlight these new inhibitors' actions through an opposite orientation than natural enzyme substrate E1′s classical one. Furthermore, molecular modeling experiments explain the better inhibitory activity of E1-ether derivative 5, as opposed to the E2-ether derivatives 6 and 10. Finally, when tested on T-47D and Z-12 cells, compounds 5, 6 and 10 did not stimulate the proliferation of these two estrogen-dependent cell lines. In fact, they reduced it. [ABSTRACT FROM AUTHOR]

Peroxisomes are essential metabolic organelles, well known for their roles in the metabolism of complex lipids and reactive ionic species. In the past 10 years, peroxisomes have also been cast as central regulators of immunity. Lipid metabolites of peroxisomes, such as polyunsaturated fatty acids (PUFAs), are precursors for important immune mediators, including leukotrienes (LTs) and resolvins. Peroxisomal redox metabolism modulates cellular immune signaling such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. Additionally, peroxisomal β-oxidation and ether lipid synthesis control the development and aspects of the activation of both innate and adaptive immune cells. Finally, peroxisome number and metabolic activity have been linked to inflammatory diseases. These discoveries have opened avenues of investigation aimed at targeting peroxisomes for therapeutic intervention in immune disorders, inflammation, and cancer. Peroxisomes are important metabolic regulators of immune cell development and function. Peroxisomes produce distinct lipids that control core cellular immune responses, including phagocytosis and secretion of inflammatory cytokines. Peroxisomes regulate cellular reactive oxygen and nitrogen species to modulate immune and inflammatory signaling. Intracellular pathogens interfere with peroxisomes in different ways to evade the peroxisome-dependent immune response and support their survival. Manipulation of peroxisome plasticity and metabolism may lead to novel therapeutics to treat immune disorders and antibiotic-resistant bacteria. [ABSTRACT FROM AUTHOR]

The hybrid systems of CuO-ZnO-Al 2 O 3 /HZSM-5 for the one-step synthesis of DME from biomass-derived syngas were prepared by four different combination methods (granule-mixing, powder-mixing, physical coating and dual-bed fixing) and characterized by N 2 adsorption, XRD, N 2 O titration, H 2 -TPR, NH 3 -TPD and TG techniques. The influences of combination method on the physicochemical properties and catalytic performances of hybrid catalyst were investigated, and the relationship among the combination method, the synergistic effect and the WGS reaction was discussed based on the composition features of the biomass-derived syngas (CO 2 -rich and H 2 -deficient). A maximum of CO conversion and DME yield was obtained over the hybrid catalyst prepared by granule-mixing method. There is a synergistic effect, which remarkably promotes the formation of DME, between the methanol synthesis and the methanol dehydration over the hybrid catalysts except for the hybrid system configured using the dual-bed fixing method. The WGS reaction, playing a pivotal role in the direct DME synthesis because of the in-situ produced hydrogen, relates to the combination method closely. An interaction between the two catalyst components arising in the combination process affects the properties of active sites and further the catalytic performances. The deactivation of the hybrid catalyst is ascribed mainly to the increase in the particle size of Cu in CuO-ZnO-Al 2 O 3. [Display omitted] • Combination method affects synergistic effect, WGS reaction and catalytic property. • Synergistic effect was observed in direct DME synthesis from biomass-derived syngas. • Hydrogen produced via WGS reaction plays an important role for direct DME synthesis. • Interaction between CZA and HZSM-5 changes the amount and property of active site. • Deactivation of hybrid catalyst is ascribed to the increase in d Cu in CZA component. [ABSTRACT FROM AUTHOR]

Oxime ethers are of great importance in the field of pharmaceutical chemicals and polymer materials. Herein, we have developed a straightforward synthetic method to prepare oxime ethers starting from tetrahydrofuran or other cyclic ethers and various oxime derivatives with tetrabromomethane as a mediator. A plausible mechanism indicates that tetrabromomethane is first cleaved by visible light irradiation, and the derived radicals transform tetrahydrofuran into its cationic species, which then reacts with oxime to form the target oxime ethers with the formation of a C–O bond. This novel oxidative cross-coupling reaction can be carried out under transition metal-free and mild conditions with good functional group tolerance, and is easy to scale-up. [ABSTRACT FROM AUTHOR]

We report that O‐selective arylation of 2‐ and 4‐pyridones with arylboronic acids is affected by a modular, bismacycle‐based system. The utility of this umpolung approach to pyridyl ethers, which is complementary to conventional methods based on SNAr or cross‐coupling, is demonstrated through the concise synthesis of Ki6783 and picolinafen, and the formal synthesis of cabozantib and golvatinib. Computational investigations reveal that arylation proceeds in a concerted fashion via a 5‐membered transition state. The kinetically‐controlled regioselectivity for O‐arylation—which is reversed relative to previous BiV‐mediated pyridone arylations—is attributed primarily to the geometric constraints imposed by the bismacyclic scaffold. [ABSTRACT FROM AUTHOR]

We report that O‐selective arylation of 2‐ and 4‐pyridones with arylboronic acids is affected by a modular, bismacycle‐based system. The utility of this umpolung approach to pyridyl ethers, which is complementary to conventional methods based on SNAr or cross‐coupling, is demonstrated through the concise synthesis of Ki6783 and picolinafen, and the formal synthesis of cabozantib and golvatinib. Computational investigations reveal that arylation proceeds in a concerted fashion via a 5‐membered transition state. The kinetically‐controlled regioselectivity for O‐arylation—which is reversed relative to previous BiV‐mediated pyridone arylations—is attributed primarily to the geometric constraints imposed by the bismacyclic scaffold. [ABSTRACT FROM AUTHOR]

Cu-modified SO 4 2−/ZrO 2 catalysts (X Cu-SZ) with different Cu loading contents were prepared by sulfation of ZrOCl 2 ·8H 2 O with (NH 4) 2 SO 4 to form SO 4 2−/ZrO 2 (SZ) followed by impregnation of SZ with a Cu precursor. The resulting X Cu-SZ catalysts combined with a CuO–ZnO–ZrO 2 catalyst were tested for CO 2 hydrogenation to dimethyl ether (DME). The results indicated that the unmodified SZ catalyst exhibited the maximum DME yield (3.7%) which was 2.0–2.6 times higher than the DME yield of all X Cu-SZ catalysts at the beginning of reaction. However, the DME yield over the unmodified SZ catalyst rapidly decreased, while that of all X Cu-SZ catalysts gradually increased during the time-on-stream experiment. After 100 h, the 6 wt% Cu-modified SZ catalyst achieved the maximum DME yield of 3.2% at 260 °C and 20 bar, while the DME yield of the unmodified SZ catalyst was only 2.5%. The NH 3 -TPD and XPS analyses indicated that more strong acid sites were present on the unmodified SZ catalyst, resulting in a coke formation and thus the rapid deactivation. For the X Cu-SZ catalysts, Cu0 was formed on the surface of SZ after the reduction with H 2 which accounted for the active site of hydrogenolysis of methanol to methane. During the time-on-stream experiment, Cu0 was progressively transformed to Cu 2 S through poisoning, leading to the continued increase of DME yield. [Display omitted] • The Cu addition on SO 4 2−–ZrO 2 remarkably reduced the number of strong acid sites. • Less amount of coke formation was observed on Cu-modified SO 4 2−–ZrO 2 catalysts. • Cu0 formed after H 2 pretreatment promoted undesired CH 4. • Cu0 was converted to Cu 2 S during the reaction which reduced the CH 4 formation. • The decrease of CH 4 was accompanied by the increase of DME formation. [ABSTRACT FROM AUTHOR]

Herein, we report the first example of diazotization of aminopyridines and aminoquinolines with t-BuONO in hexafluoropropan-2-ol in the absence of acids or other initiators. For aminopyridines, this reaction is the first general route toward 2-, 3-, and 4-[(1,1,1,3,3,3-hexafluoropropan-2-yl)oxy]pyridines. [ABSTRACT FROM AUTHOR]

In this study, starting from 1H‐1,2,4‐triazole, a new series of aliphatic ether derivatives containing phenyl and 1H‐1,2,4‐triazole groups together were synthesized using reduction and Williamson ether synthesis mechanisms, respectively. The molecular structures of the synthesized compounds were characterized by fourier‐transform infrared spectroscopy (FT‐IR), 1H and 13C nuclear magnetic resonance (1H NMR and 13C NMR), mass spectroscopy, and elemental analysis techniques. All synthesized compounds were screened against three different human cancer cell lines, including colon, lung, and liver cancer cells. Some of the compounds showed exceptionally high antiproliferative effects against all three cancer cell lines, with IC50 values much lower than the positive control drug bendamustine. In addition, molecular docking studies were performed to support the in vitro results and the interaction types and amino acids that play key roles in the binding of the compounds to enzymes were identified. Finally, the potential of these compounds to be drugs and their drug‐likeness properties were evaluated by absorption, distribution, metabolism, and excretion‐toxicity (ADMET) calculations and it was determined that the compounds could be drug candidates with the capacity to be effective and safe drugs for use in the treatment of different diseases. [ABSTRACT FROM AUTHOR]