Addition Of MeOH Research Articles

Enantioselective Copper-Catalyzed Ring-Opening Diboration of Arylidenecyclopropanes to Access Chiral Skipped 1,4- and 1,3-Diboronates.

Two enantioselective approaches to synthesize chiral skipped diboronate compounds have been developed, relying on copper-catalyzed one-pot asymmetric ring-opening diboration of arylidenecyclopropanes. A wide range of arylidenecyclopropanes react smoothly with HBpin in the presence of CuOAc and (R)-DTBM-Segphos, affording chiral 1,4-diboronates with high enantioselectivity (up to 99% ee). Meanwhile, a variety of arylidenecyclopropanes react selectively with HBpin and B2pin2 in the presence of CuOAc and (S,S)-Ph-BPE with the sequential addition of MeOH, providing chiral 1,3-diboronates with high enantioselectivity (up to 98% ee). These enantioenriched 1,3- and 1,4-diboronates can undergo various enantiospecific transformations with minimal loss of their enantiopurity. Mechanistic studies reveal that these two diboration processes start with CuH-catalyzed ring-opening hydroboration of arylidenecyclopropanes to form a mixture of Z/E-homoallyl boronate intermediates, which subsequently undergo enantioselective CuH-catalyzed second hydroboration or Cu-Bpin-catalyzed protoboration to produce chiral 1,4-diboronates or 1,3-diboronates, respectively.

Thianthrenation-promoted photoinduced alkene difunctionalization and aryl allylation with Morita-Baylis-Hillman adducts.

An organophotoredox-catalyzed alkoxyallylation of feed-stock olefins, through thianthrenation using a Morita-Baylis-Hillman adduct as an allylating agent, is described. Site-selective addition of MeOH to an alkene-thianthrenium salt and its subsequent conversion into a nucleophilic radical species forms the basis of this unique difunctionalization strategy. The scope is also expanded into radical aryl allylation.

Chiroptical switching of molecular universal joint triggered by complexation/release of a cation: A stepwise synergistic complexation

Pillar[5]arene-based molecular universal joints (MUJs), bearing fused crown ether subring (MUJ1 and MUJ3) or a ring without ether oxygen atom (MUJ2), were synthesized and enantio‑differentiated. Significant chiral inversion was observed for the crown ether-fused MUJs upon the addition of equivalent cations Na+, showing an anisotropy (g) factor of 0.014, while alkyl subring-fused MUJ2 showed no CD inversions. Unprecedentedly, sodium ion triggered rolling-in motion of the subring to the pillar[5]arene cavity was verified, and the synergistic noncovalent interaction of cation-π interactions and CH···π interactions were responsible for the stabilized self-included conformers. The addition of MeOH or competitive hosts 15-crown-5 ether disassembled the complex of MUJ1 and Na+ followed by a rolling-out of the subring, which made the sodium-ion triggered chiroptical switching reversible.

Biomimetic Synthesis of Cyanogramides B and C.

Marinacarboline E and cyanogramides B and C from the marine-derived bacterium Actinoalloteichus cyanogriseus have been synthesized. The key step is the Baeyer-Villiger oxidation of marinacarboline E to a ketene aminal via O → N acetyl migration, followed by addition of water or MeOH. Replacing the phenylethyl by a styryl side chain afforded dehydromarinacarboline E that was oxidized to a tetracyclic aminal. This study contributes to the chemical understanding of the enzymatic conversions in the biosynthesis of the cyanogramides.

Establishing the Reaction Pathways of the Catalytic Conversion of Erythrulose to Sulphides of Alpha‐Hydroxy Thioesters and Esters

AbstractSulphides of alpha‐hydroxy thioesters and esters (SAH(T)Es) are important fine chemicals and have great potential as platform molecules. SAH(T)Es are typically synthesized from fossil sources while little is known regarding their synthesis from carbohydrates. We report our findings about the one‐pot chemocatalytic conversion of erythrulose (ERU) to SAH(T)Es. Sn, Mo and W chlorides were the most selective catalysts towards the synthesis of S‐butyl‐4‐butylthio‐2‐hydroxybutanethioate (BBTHBT) in 1‐BuSH. The selectivity towards BBTHBT was impacted by the formation of different thioacetals (TAs). The addition of either KOH, H2O or MeOH was effective to decrease TAs formation and increase selectivity towards BBTHBT (or its ester). A kinetic profile, in situ 13C NMR measurements and experiments at different temperatures complement our studies to unravel the complicated reaction network involved in the conversion of ERU to SAH(T)Es. This insight provides a solid foundation for future improvements in the sustainable synthesis of SAH(T)Es.

Aggregation of Amphiphilic Carbocyanines: Fluorination Favors Cylindrical Micelles over Bilayered Tubes.

The synthesis of a new amphiphilic 5,5',6,6'-tetrachlorobenzimidacarbocyanine dye derivative with -(CH2)2-(CF2)5-CF3 chains attached to the nitrogen atoms in the 1,1'-position, CF8O3, is reported. Depending on the dye concentration and the addition of MeOH, CF8O3 forms J- and H-aggregates in aqueous solutions. The aggregation behavior was investigated using steady-state absorption, linear dichroism, and fluorescence spectroscopy, as well as by cryogenic transmission electron microscopy (cryo-TEM). The J-band of the MeOH-free solution is monomer-like, rather broad, and less red-shifted with respect to the monomer absorption, indicating weak excitonic coupling and disorder effects. Cryo-TEM reveals a diversity of supramolecular structures, wherein linear and branched cylindrical micelles dominate. It is concluded that the high stiffness of fluoroalkyl chains does not allow the chains to splay and completely fill up the hydrophobic gap between opposing chromophores. This destabilizes the bilayers and favors the micellar structure motifs instead. The aggregates appearing at 30% MeOH show a split absorption spectrum consisting of a broad blue-shifted H-band and an accompanying sharp red-shifted J-band with perpendicular polarizations. These HJ-type aggregates are also composed of micellar fibers, but these bundle into rope-like strands. For 10% MeOH, a narrow bilayered tube is the dominating morphology. The observed MeOH dependence of aggregation reveals a clear cosolvent effect.

Chemical Recycling of Polyhydroxybutyrate (PHB) into Bio-Based Solvents and Their Use in a Circular PHB Extraction

Two novel protocols for the chemical valorization of polyhydroxybutyrate (PHB) were developed, aiming at the production of two bio-based molecules: methyl 3-hydroxybutyrate (MHB) and methyl 3-methoxybutyrate (MMB). Optimized reaction conditions were applied to pure PHB and PHB inclusions inside bacterial cells as starting materials. MHB was synthesized through a single-step catalytic methanolysis, while MMB was synthesized through a three-step process: thermolytic distillation to give crotonic acid (CA), esterification to give methyl crotonate (MC), and oxa-Michael addition of MeOH. The obtained MHB and MMB were tested as solvents for the recovery of PHB itself both from freeze-dried single strain cultures (SSC) and mixed microbial cultures (MMC) with low to medium contents of PHB (22–57 wt %). High PHB recovery was achieved: up to 96 ± 1% through MHB and up to 98 ± 1% through MMB. Extraction from MMC slurry (with a PHB content of 39% on dry weight) was also performed, recovering 77 ± 2% using MHB and 92 ± 2% using MMB. High purities and excellent molecular weights and polydispersity indexes of extracted PHB were obtained with both MHB and MMB. Solubility in water, octanol/water partition coefficients (log Kow), and aerobic ready biodegradability of both solvents were also evaluated.

Catalytic Reduction of Graphene Oxide Membranes and Water Selective Channel Formation in Water-Alcohol Separations.

Graphene oxide (GO) is a promising membrane system for chemical separation applications due to its 2-D nanofluidics properties and an ability to control interplanar spacing for selectivity. The permeance of water, methanol (MeOH) and isopropyl alcohol (IPA) through 5 µm thick membranes was found to be 0.38 ± 0.15, 0.33 ± 0.16 and 0.42 ± 0.31 LMH/bar (liter/m2·h·bar), respectively. Interestingly, the permeance of a water–alcohol mixture was found to be dramatically lower (~0.01 LMH/bar) than any of its components. Upon removing the solvent mixture, the transmembrane flux of the pure solvent was recovered to near the original permeance. The interlayer space of a dried GO membrane was found to be 8.52 Å, which increased to 12.19 Å. 13.26 Å and 16.20 Å upon addition of water, MeOH and IPA. A decrease in d-space, about 2 Å, was consistently observed when adding alcohol to water wetted GO membrane and an optical color change and reduction in permeance. A newly proposed mechanism of a partial reduction of GO through a catalytic reaction with the water–alcohol mixture is consistent with experimental observations.

Sesquiterpene Lactones from Calea pinnatifida: Absolute Configuration and Structural Requirements for Antitumor Activity.

This work describes the chromatographic fractionation of the aerial parts of Calea pinnatifida and the structural characterization and determination of the absolute configuration of the isolated compounds as well as their antitumor potential. The HPLC fractionation of the CH2Cl2 phase of the MeOH extract from the leaves of C. pinnatifida led to the isolation of two related sesquiterpene lactones (STLs): calein C (1) and calealactone B (2). Additionally, during the purification process, a derivative of calein C (3) was formed as a product of the Michael addition of MeOH. The structures of Compounds 1–3 were established based on spectroscopic and spectrometric data, while the absolute stereochemistry was established by vibrational circular dichroism. In order to evaluate the effect of the conjugated double bonds on the cytotoxic activity of STLs, Compounds 1–3 were tested against anaplastic (KTC-2) and papillary (TPC-1) thyroid carcinoma cells. Calein C was the most active of the STLs, and displayed activity against both KTC-2 and TPC-1. On the other hand, the calein C derivative (3) was the least cytotoxic of all the compounds tested. These results are promising and suggest the importance of studying sesquiterpene lactones isolated from C. pinnatifida in terms of antitumor activity, especially considering the effects of α,β-unsaturated carbonyl systems.

Selective Recognition of Chloride by a 24‐Membered Macrocyclic Host with a Hydrophobic Methylenepyrene Substituent

A structure‐guided design, synthesis, and characterization of neutral unclosed cryptand functionalized with a bulky and hydrophobic 1‐methylene‐pyrene substituent is described. The host selectively binds spherical chloride (Cl–) over bigger and more basic carboxylates (MeCO2–, PhCO2–) and dihydrogenphosphate (H2PO4–) in a competitive [D6]DMSO + 0.5 % H2O solvent mixture. The capture of chloride is accompanied by formation of sandwich‐type complex stabilized by π–π and CH–π interactions. Step‐wise addition of MeOH triggers release of the cargo in a controllable manner.

Total Synthesis of (-)-Sinulariadiolide. A Transannular Approach.

The constrained tricyclic skeleton of the nor-cembranoid sinulariadiolide (1) with a nine-membered nexus was obtained by a cascade of transannular Michael reaction, carbonate elimination, butenolide formation, and spontaneous oxa-Michael addition of MeOH. The required macrocyclic precursor was prepared by ring-closing alkyne metathesis followed by trans-hydrostannation/carbonylation.

Transition-Metal-Free Multicomponent Approach to Stereoenriched Cyclopentyl-isoxazoles through C-C Bond Cleavage.

An efficient multicomponent reaction for the synthesis of stereoenriched cyclopentyl-isoxazoles from camphor-derived α-oximes, alkynes, and MeOH is reported. Our method involved a series of cascade transformations, including the in situ generation of an IIII catalyst, which catalyzed the addition of MeOH to a sterically hindered ketone. Oxidation of the oxime, and rearrangement of the α-hydroxyiminium ion generated a nitrile oxide in situ, which, upon [3+2] cycloaddition reaction with an alkyne, delivered the regioselective product. This reaction was very selective for the syn-oxime. This multicomponent approach was also extended to the synthesis of a new glycoconjugate, camphoric ester-isoxazole C-galactoside.

Mechanisms of Rhodium(III)-Catalyzed C-H Functionalizations of Benzamides with α,α-Difluoromethylene Alkynes.

The rhodium(III)-catalyzed C-H functionalizations of benzamides with α,α-difluoromethylene alkynes have been investigated by means of density functional theory calculations. The computations show that after the formation of seven-membered rhodacycle via consecutive N-H deprotonation/C-H activation/migratory insertion, a novel redox-neutral process without the engagement of otherwise widely accepted Rh(V) nitrenoid species has been formulated in the hydroarylation reaction. It turns out that the seven-membered rhodacycle undergoes a concerted Lossen rearrangement/migration of OPiv from N to Rh to generate the isocyanate intermediate, from which the ensuing nucleophilic addition of MeOH and protodemetalation lead to the generation of final products. By preventing formation of Rh(V) nitrenoid species, the intriguing role of fluorine substituents in hydroarylation reaction has also been disclosed. Furthermore, the coordination of carbonyl oxygen of OPiv group to the Rh center proves to be crucial for both [4 + 2] annulation and hydroarylation. However, in the case of using directing group with N-OMe, the lack of such assistance would engender a considerable buildup of energy with respect to the transition state, making both [4 + 2] annulation and hydroarylation processes kinetically unfavorable. Accordingly, the alternative [4 + 1] annulation takes place as the most favored pathway via consecutive twofold β-F eliminations.

Steel wool and carbonyl iron powder activation of persulphate for the degradation of pollutants

Commercial zerovalent iron (ZVI) – as steel wool and carbonyl iron powder – activation of persulphate (PS) has been demonstrated to be effective in the degradation of four important water pollutants, namely, orange G (OG), salicylic acid (SA), phenol (Ph), and 1-naphthylamine (1NA) in the presence or absence of methanol (MeOH). The addition of MeOH mimics the presence of industrial solvents and/or feedstuff in real industrial wastewater. The alcohol had a more retarding effect on the degradation of an aromatic pollutant relatively resistant to oxidation such as SA due to the presence of an electron-withdrawing group compared to a pollutant such as 1NA that has an electron-donating group. The azo bond in OG constituted a structural weakness leading to a comparatively more effective degradation of the aromatic moieties. Fe2+ was not only less effective than the commercial ZVI in activating PS; it was also more significantly retarded in its activity by MeOH. In addition, the surfaces of the ZVI were not oxidised, an advantage over ZVI nanoparticles, and they required no prior pretreatment indicating the probable suitability of waste iron filings for PS activation. As an activator of PS, ZVI is optimised at a size range of 0.1 μm < d < 100 μm. It was also demonstrated that the poor optimisation of PS concentration not only increases oxidant consumption or treatment time but also results in the persistence of undesirable aromatic degradation by-products. These results are important for the development of low-cost and effective industrial wastewater treatment schemes.

Exergy losses in auto-ignition processes of DME and alcohol blends

The exergy losses in the auto-ignition processes of binary blends of dimethyl ether (DME) and methanol (MeOH)/ethanol (EtOH) were numerically studied in an adiabatic constant-volume system. Three detailed kinetic mechanisms for the DME/alcohol blends were employed in the auto-ignition simulation at changed temperature, pressure, equivalence ratio and oxygen concentration conditions. Four reaction stages, namely the fuel-series reaction stage, the fuel-fragment reaction stage, the H2O2 loop reaction stage and the H2-O2 reaction stage were defined for the auto-ignition processes based on the reaction pathway analysis, and the exergy destructions in each stage were evaluated for different fuels. It was observed that the exergy loss characteristics calculated by three mechanisms were consistent. Meanwhile, increased initial pressure and reduced oxygen concentration could lower down the overall exergy losses. In addition, MeOH/EtOH addition does not show significant effects on the total exergy losses but the MeOH addition was more effective than EtOH in extending the area of the minimum exergy losses. Furthermore, the interaction effects between the reaction kinetics of alcohols and DME on the exergy loss characteristics were analyzed at the low and high initial temperatures, respectively. The exergy loss rates of different fuels featured triple-peak traces as the initial temperature was located at the low temperature region, while double-peak traces were shown at the high initial temperature condition. At the low initial temperature conditions, MeOH/EtOH addition to DME suppressed the low-temperature reactions, causing the reduced magnitude of the first peak in the exergy loss rate curves. In addition, the magnitude of the second peak increased with MeOH addition while decreased with EtOH addition. The magnitude of the third peak showed insignificant change with MeOH/EtOH addition. At both low and high initial temperatures, the addition of MeOH to DME increases the exergy losses by the H2O2 loop reactions while decreases the exergy losses by the fuel-fragment reactions. In contrast, the addition of EtOH decreases the exergy losses by the H2O2 loop reactions while increases the exergy losses by the fuel-fragment reactions.

Self-assembly and omniphobic property of fluorinated unit end-functionalized poly(methyl methacrylate)

Abstract The self-assembly behavior of fluorinated unit end-functionalized poly(methyl methacrylate) (PDFHM- ef -PMMA) in solution and its influence on the surface microstructure, elemental composition and omniphobic property of cast film was investigated in this work. Specifically, three mixed solutions of tetrahydrofuran (THF)/methanol (MeOH), THF/H 2 O and THF/H 2 O/MeOH in various compositions were employed separately as the selective solvents. In THF/MeOH solution, the aggregate morphologies of PDFHM- ef -PMMA changed gradually from core-shell spheres to worm, and then to elliptical vesicles as MeOH content increased. In THF/H 2 O solution, spherical and bowl-shaped aggregates with significantly larger sizes than those in THF/MeOH solution were favored despite lower H 2 O content. The further addition of MeOH to THF/H 2 O mixture could reduce the size of aggregate but hardly change original aggregate morphology. During the film formation process, those self-assembled aggregates in THF/MeOH solution fused with one another to form a smooth surface. When such surface was fully covered by fluorinated segments, the outstanding hexadecane and water slide-off properties and ink-resistant property required for antifouling application were demonstrated. Instead, the aggregates formed in THF/H 2 O/MeOH mixture were subjected to secondary aggregation of PDFHM- ef -PMMA chains during solvent evaporation, leading to the formation of a particulate film with poor adhesion towards glass plate and hexadecane-repellent property.

Colloidal Dispersion of a Perfluorosulfonated Ionomer in Water⁻Methanol Mixtures.

We have investigated the dispersion state of a perfluorosulfonated ionomer (PFSI; Nafion®) in aqueous dispersion and the effect of methanol (MeOH) added to the aqueous dispersion by small-angle X-ray scattering (SAXS) as well as static and dynamic light scattering (SLS and DLS, respectively). Although both electrostatic and hydrophobic interactions of PFSI are expected to be strong in the dispersions, SAXS profiles obtained were satisfactorily fitted by the spherical particle model of a bimodal molar mass distribution. The rod-like aggregate model proposed in previous papers was denied at least for the present PFSI dispersion. Although the SAXS profiles exhibited a weak peak and the auto-correlation functions of DLS showed a log-time decay by the “repulsive cage effect” due to the long-ranged electrostatic interaction among PFSI particles, the concentration dependence of SLS results was probably normal because the cancellation of the electrostatic and hydrophobic interactions. The addition of MeOH into the aqueous dispersion of PFSI weakened both the hydrophobic and electcrostatic interactions of PFSI, and it is rather difficult to classify whether MeOH is a good or poor solvent (dispersant) for PFSI.

Glucopyranosylidene-Spiro-Thiazolinones: Synthetic Studies and Determination of Absolute Configuration by TDDFT-ECD Calculations.

Reactions of O-peracylated C-(1-bromo-β-d-glucopyranosyl)formamides with thioamides furnished the corresponding glucopyranosylidene-spiro-thiazolin-4-one. While O-debenzoylations under a variety of conditions resulted in decomposition, during O-deacetylations the addition of MeOH to the thiazolinone moiety was observed, and with EtOH and water similar adducts were isolated or detected. The structure and stereochemistry of the new compounds were established by means of NMR and electronic circular dichroism (ECD) data supported by time-dependent density functional theory ECD (TDDFT-ECD) calculations. TDDFT-ECD calculations could efficiently distinguish the proposed epimeric products having different absolute configuration in the spiro heterocyclic ring.

Transition-Metal-Free Reductive Coupling of 1,3-Butadienes with Aldehydes Catalyzed by Dibutyliodotin Hydride.

In this study, the Bu2SnIH-catalyzed direct coupling of 1,3-dienes with aldehydes was developed. This reaction could be suitable for coupling without the use of transition-metal catalysts. Many types of aldehydes were applied to this reaction. The addition of MeOH promoted the catalytic cycle.

Tuning Metabolome Coverage in Reversed Phase LC-MS Metabolomics of MeOH Extracted Samples Using the Reconstitution Solvent Composition.

Considering the physicochemical diversity of the metabolome, untargeted metabolomics will inevitably discriminate against certain compound classes. Efforts are nevertheless made to maximize the metabolome coverage. Contrary to the main steps of a typical liquid chromatography-mass spectrometry (LC-MS) metabolomics workflow, such as metabolite extraction, the sample reconstitution step has not been optimized for maximal metabolome coverage. This sample concentration step typically occurs after metabolite extraction, when dried samples are reconstituted in a solvent for injection on column. The aim of this study was to evaluate the impact of the sample reconstitution solvent composition on metabolome coverage in untargeted LC-MS metabolomics. Lysogeny Broth medium samples reconstituted in MeOH/H2O ratios ranging from 0 to 100% MeOH and analyzed with untargeted reversed phase LC-MS showed that the highest number of metabolite features (n = 1500) was detected in samples reconstituted in 100% H2O. As compared to a commonly used reconstitution solvent mixture of 50/50 MeOH/H2O, our results indicate that the small fraction of compounds increasing in peak area response by the addition of MeOH to H2O, 5%, is outweighed by the fraction of compounds with decreased response, 57%. We evaluated our results on human serum samples from lymphoma patients and healthy control subjects. Reconstitution in 100% H2O resulted in a higher number of significant metabolites discriminating between these two groups than both 50% and 100% MeOH. These findings show that the sample reconstitution step has a clear impact on the metabolome coverage of MeOH extracted biological samples, highlighting the importance of the reconstitution solvent composition for untargeted discovery metabolomics.