Alcohol Derivatives Research Articles

Comparative study of catalytic activity of tetrameric lanthanide-substituted polyoxotungstates [(Ln2XW10O38)4(W3O8)(OH)4(H2O)2]n− (X = SiIV, GeIV & PV and n = 26 or 25) for the oxidation of alcohols

The catalytic activity of tetrameric lanthanide-substituted phospho, germano and silicotungstate with the formula [(Ln2XW10O38)4(W3O8)(OH)4(H2O)2]n− (X = SiIV, GeIV & PV and n = 26 or 25) {Ln8X4W40} (X = SiIV, GeIV or PV) has been investigated for the oxidation of alcohol derivatives in homogeneous medium. The comparative study shows that the lanthanide-substituted phosphotungstates possesses better catalytic activity over the silico and germanotungstate analogues. The reaction was carried out in eco-friendly solvent (water) in presence of green oxidant (H2O2). The recovered catalysts were characterized by FT-IR spectroscopy and powder X-ray diffraction (PXRD). The catalysts are stable and can be recovered even after five consecutive cycles of reaction with only a slight loss in its catalytic activity.

Catalytic Oxidation of Veratryl Alcohol Derivatives Using RuCo/rGO Composites.

Chemoselectively oxidizing Cα -OH to C=O has been considered as a key step for the oxidative depolymerization of lignin. In this work, we design and prepare a series of composites of RuCo alloy nanoparticles and reduced graphene oxide (RuCo/rGO) with different Ru to Co ratios and explore their catalytic activities in the oxidation of veratryl alcohol derivatives, which usually serve as the model compounds for studying lignin oxidation. It is illustrated that the Ru to Co ratio determines the morphology and average size of the RuCo alloy nanoparticles on rGO, and the overall catalytic activities of the composites. The RuCo alloy nanoparticles on rGO with Ru to Co ratios of 1 : 0 to 1.2 : 1 show a unique flower-shaped morphology that increases the exposure of the active sites and thus promotes their contact with the substrates. The RuCo/rGO composites exhibit high catalytic activities for the oxidation of Cα -OH to aldehydes at 100 °C for 2 h. Additionally, the Co component affords the RuCo/rGO composites with magnetic properties that make the separation and recovery of the catalyst simple. Given the high catalytic performances and easy recovery, the RuCo/rGO composites would be potentially useful for the depolymerization of lignin.

Continuous flow organocatalyzed methoxycarbonylation of benzyl alcohol derivatives with dimethyl carbonate

Continuous flow organocatalyzed methoxycarbonylation of benzyl alcohol derivatives with dimethyl carbonate

Phosphorescent Vapochromic Responses of Copper(I) Complex Bearing Pyrazole Ligands for Detection of Alcohol Derivatives

The methodical study of trinuclear copper(I) metal complexes phosphorescent vapochromic chemosensor via metal-metal interactions for sensing various volatile organic compounds has piqued the interest of many researchers. Herein, we highlighted the performance of chemosensors trinuclear copper(I) pyrazolate complexes (2Pz1‒2Pz5) with different molecular design short alkyl side chains from the respective pyrazole ligands. The synthesized complexes had demonstrated a high phosphorescent sensing capacity of various alcohol derivatives. Due to weak metal-metal interactions, the complexes give emission bands centered around 553-644 nm at an excitation of 280 nm. We found that the only 2Pz3 chemosensors showed quenching phenomena with a significant decrease in its emission intensity of 100% for exposure in 5 minutes with irreversible performance. Interestingly, we also found that the shifting of the emission center due to the disruption of metal-metal interaction performed by chemosensor 2Pz5 resulting in the best detection performance of methanol and ethanol (∆λ= 60 nm) and propanol (∆λ = 22 nm) showing autonomous recovery within 15 minutes. Based on the findings, the specific balance, such as rigidity and amphiphilicity in the molecular design of chemosensors, is important for the detection of vapors via supramolecular interactions.

TBAF-initiated vinylation of aldehydes with trimethyl[(Z)-2-(phenylsulfanyl)-1-(trifluoromethyl)vinyl]silane

The titular compound trifluromethylated vinylsilane was readily prepared in 84% yield from stereodefined (Z)-2‑bromo-2-(trifluoromethyl)vinyl phenyl sulfide and chlorotrimethylsilane in the presence of magnesium under Barbier-type reaction conditions. The TBAF-initiated reaction of the vinylsilane and various aldehydes proceeded smoothly to give the corresponding 2-(trifluoromethyl)allyl alcohol derivatives in moderate to good yields.

Origins of Catalyst-Controlled Selectivity in Ag-Catalyzed Regiodivergent C-H Amination.

Ag-catalyzed nitrene transfer (NT) converts C-H bonds into valuable C-N bonds. These reactions offer a promising strategy for catalyst-controlled regiodivergent functionalization of different types of reactive C-H bonds, as the regioselectivity is tunable by varying the steric and electronic environments around the Ag nitrene, as well as the identity of the nitrene precursors and the tether length. Therefore, a unified understanding of how these individual factors affect the regioselectivity is key to the rational design of highly selective and regiodivergent C-H amination reactions. Herein, we report a computational study of various Ag-catalyzed NT reactions that indicates a concerted H-atom transfer (HAT)/C-N bond formation mechanism. A detailed analysis was carried out on the effects of the C-H bond dissociation enthalpy (BDE), charge transfer, ligand-substrate steric repulsions, and transition state ring strain on the stability of the C-H insertion transition states with different Ag nitrene complexes. The ancillary ligands on the Ag and the nitrene precursor identity both affect transition state geometries to furnish differing sensitivities to the BDE, tether length, and electronic effects of the reactive C-H bonds. Based on our understanding of the dominant factors that control selectivity, we established a rational catalyst and precursor selection approach for regiodivergent amination of diverse C-H bonds. The computationally predicted regiodivergent amination of β- and γ-C-H bonds of aliphatic alcohol derivatives was validated by experimental studies.

Front Cover: Visible‐Light‐Enabled Carboxylation of Benzyl Alcohol Derivatives with CO2 Using a Palladium/Iridium Dual Catalyst (ChemSusChem 3/2022)

The Front Cover shows a switchable site-selective carboxylation between benzylic C−O and aryl C−Cl moieties enabled by a palladium/iridium dual catalyst under visible light irradiation using CO2. The developed method featured the generation of highly active metallic species by the combination of amine, photosensitizer, and light irradiation without using stoichiometric amount of metal reductants. More information can be found in the Communication by Y. Jin et al.

Visible-Light-Enabled Carboxylation of Benzyl Alcohol Derivatives with CO2 Using a Palladium/Iridium Dual Catalyst.

Invited for this month's cover is the group of Nobuharu Iwasawa at Tokyo Institute of Technology. The image shows a switchable site-selective carboxylation between benzylic C-O and aryl C-Cl moieties enabled by a palladium/iridium dual catalyst under visible light irradiation. The Communication itself is available at 10.1002/cssc.202102095.

Quantum Chemical Prediction of Electron Ionization Mass Spectra of Trimethylsilylated Metabolites.

Chemical derivatization, especially silylation, is widely used in gas chromatography coupled to mass spectrometry (GC-MS). By introducing the trimethylsilyl (TMS) group to substitute active hydrogens in the molecule, thermostable volatile compounds are created that can be easily analyzed. While large GC-MS libraries are available, the number of spectra for TMS-derivatized compounds is comparatively small. In addition, many metabolites cannot be purchased to produce authentic library spectra. Therefore, computationally generated in silico mass spectral databases need to take TMS derivatizations into account for metabolomics. The quantum chemistry method QCEIMS is an automatic method to generate electron ionization (EI) mass spectra directly from compound structures. To evaluate the performance of the QCEIMS method for TMS-derivatized compounds, we chose 816 trimethylsilyl derivatives of organic acids, alcohols, amides, amines, and thiols to compare in silico-generated spectra against the experimental EI mass spectra from the NIST17 library. Overall, in silico spectra showed a weighted dot score similarity (1000 is maximum) of 635 compared to the NIST17 experimental spectra. Aromatic compounds yielded a better prediction accuracy with an average similarity score of 808, while oxygen-containing molecules showed lower accuracy with only an average score of 609. Such similarity scores are useful for annotation of small molecules in untargeted GC-MS-based metabolomics, suggesting that QCEIMS methods can be extended to compounds that are not present in experimental databases. Despite this overall success, 37% of all experimentally observed ions were not found in QCEIMS predictions. We investigated QCEIMS trajectories in detail and found missed fragmentations in specific rearrangement reactions. Such findings open the way forward for future improvements to the QCEIMS software.

A Synthetic Protocol for the Construction of Chroman‐Spiroquinazolin(thi)one Framework via a Metal‐Free, Three‐Component, Domino, Double Annulations

AbstractA three‐component domino approach for the synthesis of chroman‐spiroquinazolin(thi)ones is described. It involves a condensation of 2‐aminoacetophenones and iso(thio)cyanates followed by a hetero‐Diels‐Alder annulation with 2‐hydroxybenzyl alcohol derivatives. The reaction exhibits a broad substrate scope under a metal‐free catalytic condition.magnified image

Hydrogenative Cycloisomerization and Sigmatropic Rearrangement Reactions of Cationic Ruthenium Carbenes Formed by Catalytic Alkyne gem‐Hydrogenation

Abstractgem‐Hydrogenation of propargyl alcohol derivatives with [CpXRu(MeCN)3]PF6 (CpX=substituted cyclopentadienyl) as catalysts affords cationic pianostool ruthenium carbene complexes which are so electrophilic that they attack a tethered olefin to furnish cyclopentene products; cyclopropanation or metathesis do not compete with this novel transformation. If the transient carbenes carry appropriate propargylic substituents, however, they engage in ([2,3]‐sigmatropic) rearrangements to give enol esters (carbonates, carbamates, sulfonates) or alkenyl halides. Both pathways are unprecedented in the vast hydrogenation literature. The proposed mechanistic scenarios are in line with labeling experiments and spectroscopic data; most notably, PHIP NMR spectroscopy (PHIP=parahydrogen induced polarization) provides compelling evidence that the reactions are indeed triggered by highly unorthodox gem‐hydrogenation events.

Hydrogenative Cycloisomerization and Sigmatropic Rearrangement Reactions of Cationic Ruthenium Carbenes Formed by Catalytic Alkyne gem-Hydrogenation.

gem‐Hydrogenation of propargyl alcohol derivatives with [CpXRu(MeCN)3]PF6 (CpX=substituted cyclopentadienyl) as catalysts affords cationic pianostool ruthenium carbene complexes which are so electrophilic that they attack a tethered olefin to furnish cyclopentene products; cyclopropanation or metathesis do not compete with this novel transformation. If the transient carbenes carry appropriate propargylic substituents, however, they engage in ([2,3]‐sigmatropic) rearrangements to give enol esters (carbonates, carbamates, sulfonates) or alkenyl halides. Both pathways are unprecedented in the vast hydrogenation literature. The proposed mechanistic scenarios are in line with labeling experiments and spectroscopic data; most notably, PHIP NMR spectroscopy (PHIP=parahydrogen induced polarization) provides compelling evidence that the reactions are indeed triggered by highly unorthodox gem‐hydrogenation events.

A facile and chemoselectivity in synthesis of 4-chloro-N-(4-((1-hydroxy-2-methylpropan-2-yl)oxy)phenethyl)benzamide, the alcohol derivative of Bezafibrate

A facile method for the reduction of carboxylic acid group of Bezafibrate, an approved drug, is described. The selective reduction of carboxylic acid group to corresponding alcohol was carried out by activation of the carboxylic acid moiety via mixed anhydride followed by the addition of stoichiometric amount of NaBH4 and methanol to obtain the first alcohol variant of Bezafibrate. The reaction was completed in 5–10 min in excellent yield and purity. The new alcohol derivative was characterized by spectroscopic methods. This is the first report on this new molecule.

One-pot synthesis of dihydroquinolones by sequential reactions ofo-aminobenzyl alcohol derivatives with Meldrum's acids

The functionalized 3,4-dihydroquinolin-2-one nucleus has been assembled in good to high yields through the sequential reaction of readily available N-Ts-o-aminobenzyl alcohols with 5-substituted Meldrum's acid derivatives under mild basic conditions. Highly diastereoselective synthesis of 3-substituted-4-phenyl-1-tosyl-3,4-dihydroquinolin-2(1H)-ones was accomplished from N-(2-(hydroxy(phenyl)methyl)phenyl)-4-methylbenzenesulfonamide under the same reaction conditions. Regarding the reaction mechanism, we hypothesized that the formation of dihydroquinolones proceeds through the in situ generation of aza-o-QMs followed by conjugate addition of enolate/cyclization/elimination of acetone and CO2.

Diastereoconvergent synthesis of anti-1,2-amino alcohols with N-containing quaternary stereocenters via selenium-catalyzed intermolecular C-H amination.

We report a diastereoconvergent synthesis of anti-1,2-amino alcohols bearing N-containing quaternary stereocenters using an intermolecular direct C–H amination of homoallylic alcohol derivatives catalyzed by a phosphine selenide. Destruction of the allylic stereocenter during the selenium-catalyzed process allows selective formation of a single diastereomer of the product starting from any diastereomeric mixture of the starting homoallylic alcohol derivatives, eliminating the need for the often-challenging diastereoselective preparation of starting materials. Mechanistic studies show that the diastereoselectivity is controlled by a stereoelectronic effect (inside alkoxy effect) on the transition state of the final [2,3]-sigmatropic rearrangement, leading to the observed anti selectivity. The power of this protocol is further demonstrated on an extension to the synthesis of syn-1,4-amino alcohols from allylic alcohol derivatives, constituting a rare example of 1,4-stereoinduction.

Tetraarylphosphonium salt-catalyzed formal [3+2] cycloaddition between epoxides and trichloroacetonitrile for the synthesis of β-amino alcohol derivatives.

Efficient regioselective synthesis of β-amino alcohol derivatives, including enantioenriched ones, by a tetraarylphosphonium salt-catalyzed coupling reaction of epoxides with trichloroacetonitrile is described. Formal [3+2] cycloaddition, followed by hydrolysis, proceeded smoothly to afford N-protected β-amino alcohols in good yields.

Phytochemical Analysis and Dermo-Cosmetic Evaluation of Cymbidium sp. (Orchidaceae) Cultivation By-Products.

Cymbidium is one of the most popular genera in Orchidaceae family, commercialized either as loose flowers or as potted plants in floriculture worldwide. The non-marketable parts are typically discarded (e.g., unsuitable flowers, leaves, pseudobulbs, roots), generating an enormous quantity of unutilized biomass. The above by-products were studied through phytochemical analysis and investigated for their dermo-cosmetic potential. The initial antioxidant, anti-tyrosinase, anti-elastase, and anti-collagenase assays of the total extracts indicated that the pseudobulb and root ethyl acetate extracts were the most potent. Those extracts were then submitted to chromatographic separation leading to the isolation of 16 secondary metabolites (four phenanthrenes, three 1,4-phenanthrenquinones, three dibenzyls, two phenolic acid derivatives, two sterols, one dehydrodiconiferyl alcohol derivative, and one simple phenolic compound), including 6-hydroxy-5,7-dimethoxy-1,4-phenanthrenequinone (cymbisamoquinone), which was identified as a new natural product. In parallel, 48 metabolites were identified by UPLC-HRMS analysis of the extracts. The biological evaluation of the isolated compounds revealed that gigantol and tristin present important anti-tyrosinase activity, while bulbophyllanthrin, 3-hydroxy-2,4,7-trimethoxy-phenanthrene, marylaurencinol A, 5-hydroxy-2-methoxy-1,4-phenanthrenequinone, and ephemeranthroquinone B show dose-dependent anti-collagenase activity. In contrast to isolated metabolites, which may act selectively on specific enzymes, the initial total extracts exhibited inhibitory activity against tyrosinase, elastase, and collagenase enzymes, thus showing better prospects for use in dermo-cosmetic formulations.

SYNTHESIS OF A NEW DERIVATIVE OF KOLCHAMINE WITH PROPARGYL ALCOHOL.

SYNTHESIS OF A NEW DERIVATIVE OF KOLCHAMINE WITH PROPARGYL ALCOHOL.

Intermediates formed during natural attenuation of C9 aromatics under simulated marine conditions: Identification, transformation pathway, and toxicity to microalgae

C9 aromatics — benzene hydrocarbon containing nine carbon atoms among — leakage accident has caused serious damage to the marine ecology near Quangang District, Fujian Province, China. The ecological restoration of the accident sea area is basically realized through natural attenuation. To determine whether the natural attenuation of C9 aromatics in the marine environment will generate highly toxic intermediates, and thus cause more serious harm to marine ecology, the intermediates of C9 aromatics (n-propylbenzene, isopropylbenzene, 2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and indene) in the process of natural attenuation were studied under the marine conditions simulated by a microcosm. The acute toxic effects of 12 intermediates with longer residual time on Phaeodactylum tricornutum were also ascertained. Twenty natural attenuation intermediates of C9 aromatics were identified. These products primarily include the derivatives of phenols, aromatic alcohols, aromatic aldehydes, aromatic ketones, and aromatic acids, as well as an aromatic lactone compound. No intermediates of 1,3,5-trimethylbenzene and indene during the attenuation process were determined. The indirect photooxidation initiated by hydroxyl radical might play an essential role in the formation of intermediates of C9 aromatic. Based on the 96-h EC50 values for P. tricornutum, the toxicity of the 12 intermediates, in descending order, was: 4-ethylphenol, 2-methylacetophenone, 2,3-dimethylbenzyl alcohol, 4-methylacetophenone, 3-methylacetophenone, 1-phenyl-1-propanol, 1-(2-methylphenyl) ethanol, 2-phenyl-2-propanol, 3,4-dimethylbenzoic acid, 2,4-dimethylbenzoic acid, 2,5-dimethylbenzoic acid, then 4-tolylacetic acid. The 96-h EC50 values of the intermediates of C9 aromatics to P. tricornutum ranged from 8.4 to 199.1 mg/L, which were lower than that of their corresponding parent compound. The findings provided essential fundamental insights for the assessment of marine environmental risk of C9 aromatics leakage accidents, and subsequent emergency disposal countermeasures.

Visible-Light-Enabled Carboxylation of Benzyl Alcohol Derivatives with CO2 Using a Palladium/Iridium Dual Catalyst.

A highly efficient carboxylation of benzyl alcohol derivatives with CO2 using a palladium/iridium dual catalyst under visible-light irradiation was developed. A wide range of benzyl alcohol derivatives could be employed to provide benzylic carboxylic acids in moderate to high yields. Mechanistic studies indicated that the oxidative addition of benzyl alcohol derivatives was possibly the rate-determining-step. It was also found that a switchable site-selective carboxylation between benzylic C-O and aryl C-Cl moieties could be achieved simply by changing the palladium catalyst.