Carbonyl Compounds Research Articles

Recent Advances in NHC-Catalyzed Chemoselective Activation of Carbonyl Compounds.

N-Heterocyclic carbenes (NHCs) catalysts have been employed as effective tools in the development of various reactions, which have made notable contributions in developing diverse reaction modes and generating significant functionalized molecules. This review provides an overview of the recent advancements in the chemo- and regioselective activation of different aldehydes using NHCs, categorized into five parts based on the different activation modes. A brief conclusion and outlook is provided to stimulate the development of novel activation modes for accessing functional molecules.

Continuous Flow Process for Carbonyl and α,β-Unsaturated Carbonyl Compounds Reduction Using NaBH4 Solutions: Toward Implementation of Luche Reduction in Flow

Continuous Flow Process for Carbonyl and α,β-Unsaturated Carbonyl Compounds Reduction Using NaBH₄ Solutions: Toward Implementation of Luche Reduction in Flow

Deoxygenative Coupling of Carbonyl Compounds with Alkynes under Molybdenum Catalysis

Deoxygenative Coupling of Carbonyl Compounds with Alkynes under Molybdenum Catalysis

Recent Progress in the Synthesis of α‐Hydroxy Carbonyl Compounds with ThDP‐dependent Carboligases

AbstractThiamine diphosphate (ThDP) dependent carboligases catalyze the formation of carbon‐carbon bonds. These enzymes are prominent biocatalysts for the production of valuable α‐hydroxy carbonyl compounds, which serve as key building blocks in the synthesis of various pharmaceuticals and fine chemicals. Carboligases act in selective manner to afford regio‐ and stereochemically defined products from simple starting materials. This review explores the catalytic prowess of carboligases for synthetic purposes and is aimed at providing a selection tool of enzymes for particular sets of substrates or desired products. The comprehensive overview encompasses structural insights, relationships of the currently known sequence space and practical applications with a focus on recent literature, showcasing carboligases as potent tools for sustainable and efficient synthesis.

Palladium Catalyzed Selective 1,4‐Dihydrosilylation of Alkynones

AbstractAn efficient and selective Pd‐catalyzed 1,4‐dihydrosilylation of alkynones has been firstly described to provide a convenient access to β‐aryl carbonyl compounds under mild conditions. Various β‐aryl carbonyl compounds have been synthesized with good yields and functional group tolerance. β‐aryl carbonyl products have been shown to be further application in the synthesis of secondary alcohol, silyl‐ether, trifluoromethylsilyl‐ether and vinyl acetate derivative.

Exploring the impact of malondialdehyde and 4-hydroxy-2-nonena on myofibrillar protein structure: A proteomic analysis

In this investigation, the impacts of malondialdehyde (MDA), 4-hydroxy-2-nonena (HNE), and their combinations on the structural characteristics of myofibrillar proteins (MP) were examined using endogenous fluorescence, Fourier transform infrared spectrum (FTIR) and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). The potential binding mechanisms were also explored using LC-MS/MS and proteomics techniques. The findings indicated that various reactive carbonyl compounds (RCCs) displayed distinct oxidation performances in the oxidation of myofibrillar proteins. Samples containing HNE (HMP and MHMP groups) exhibited a more pronounced ability to oxidize MP than those containing MDA, as evidenced by their higher carbonyl content and lower sulfhydryl content. The MHMP group demonstrated the greatest surface hydrophobicity and Schiff base content but the lowest fluorescence intensity, suggesting that MDA and HNE synergistically altered MP conformation. Moreover, the alteration by RCCs notably modified the secondary structure of MP. Among these, HMP triggered the unfolding of MP molecules, resulting in the lowest α-helix and highest β-sheet ratio. The SDS‒PAGE results suggested that MDA oxidation promoted the crosslinking of MP molecules. At the same time, HNE caused the degradation of MP, as indicated by the decrease in the intensity of the high-molecular-weight bands. Proteomic analysis suggested that lysine residues distributed in the tail region of myosin were the main binding sites for MDA, whereas HNE preferentially modified methionine located at the myosin head. Additionally, HNE-induced protein degradation dominated RCC-induced oxidation reactions. These findings provide deeper insights into the mechanisms underlying quality changes induced by lipid oxidation products in MP-based food systems.

[Fe(NCMe)6](BF4)2 is a bifunctional catalyst for styrene aziridination by nitrene transfer and heterocycle expansion by subsequent dipolar insertion

The solvated iron(II) salt [Fe(NCMe)6](BF4)2 (Me = methyl) is shown to be a bifunctional catalyst with respect to aziridination of styrene. The salt serves as an active catalyst for nitrene transfer from PhINTs to styrene to form 2-phenyl-N-tosylaziridine (Ph = phenyl; Ts = tosyl, –S{O}2–p-C6H4Me). The iron(II) salt also acts as a Lewis acid in non-coordinating CH2Cl2 solution, to catalyze heterolytic CN bond cleavage of the aziridine and insertion of dipolarophiles. The 1,3-zwitterionic intermediate is presumably supported by interaction of the metal dication with the anion, and by resonance stabilization of the carbocation. Nucleophilic dipolarophiles then insert to give a five-membered heterocyclic ring. The result is a two-step cycloaddition, formally [2 + 1 + 2], that is typically regiospecific, but not stereospecific. This reaction mechanism was confirmed by conducting a series of one-step, [3 + 2] additions of unsaturated molecules into pre-formed 2-phenyl-N-tosylaziridine, also catalyzed by [Fe(NCMe)6](BF4)2. Relevant substrates include styrenes, carbonyl compounds and alkynes. These yield five-membered heterocylic rings, including pyrrolidines, oxazolidines and dihydropyrroles, respectively. The reaction scope appears limited only by the barrier to formation of the dipolar intermediate, and by the nucleophilicity of the captured dipolarophile. The bifunctionality of an inexpensive, earth-abundant and non-toxic catalyst suggests a general strategy for one-pot construction of heterocyclic rings, as demonstrated specifically for pyrrolidine ring formation.

Glycerol Electrolyzer with Graphite Anode and Cathode Produces Carbonyl Compounds and Hydrogen: Background Electrocatalysis of a "Nonparticipating" Current Collector.

This study unveils a novel role of bare graphite as a catalyst in glycerol electrooxidation and hydrogen evolution reactions, challenging the prevailing notion that current collectors employed in electrolyzers are inert. Half-cell experiments elucidate the feasibility of glycerol oxidation and hydrogen production on bulk graphite electrodes at potentials exceeding 1.7 V. The investigation of varying glycerol concentrations (0.05 to 1.5 mol L-1) highlights a concentration-dependent competition between glycerol electrooxidation and oxygen evolution reactions. Employing an H-type glycerol electrolyzer, polarization curves reveal significant activation polarization attributed to the low electroactivity of the anode. Glycerol electrolysis at different concentrations yields diverse product mixtures, including formate, glycolate, glycerate, and lactate at the anode, with concurrent hydrogen generation at the cathode. The anolyte composition changes with glycerol concentration, resulting in less-oxidized compounds at higher concentrations and more oxidized compounds at lower concentrations. The cell voltage also influences the product formation selectivity, with an increased voltage favoring more oxidized compounds. The glycerol concentration also affects hydrogen production, with lower concentrations yielding higher hydrogen amounts, peaking at 3.5 V for 0.05 mol L-1. This model quantitatively illustrates graphite's contribution to current and product generation in glycerol electrolyzers, emphasizing the significance of background current and products originating from current collectors if in contact with the reactants. These results have an impact on the efficiency of the electrolyzer and raise questions regarding possible extra non-noble "nonparticipating" current collectors that could affect overall performance. This research expands our understanding of electrocatalysis on graphite surfaces with potential applications in optimizing electrolyzer configurations for enhanced efficiency and product selectivity.

A DFT and catalytic studies of recyclable chitosan based heterogeneous Cu(II) catalyst for the oxidation of tetralin

The oxidation of hydrocarbons is an essential transformation for converting petroleum-based raw material into useful chemicals like diols, epoxides, alcohols, and carbonyl compounds. In this context, a chitosan (Cs) based heterogeneous catalyst, {Cu(II)[Cs-L1-L2]Cl2} was developed by the coordination of two different Schiff base ligands, L1 [Cs-HACP] and L2 [ANI-HACP] with the chitosan and followed by complexation with CuCl2·2H2O The prepared catalyst {Cu(II)[Cs-L1-L2]Cl2} was characterized by different techniques such as Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), Brunauer-Emmett-Teller (BET) surface area, Powder X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Ultraviolet visible near-infrared (UV–VIS-NIR), X-Ray photoelectron spectroscopy (XPS) and Density Functional Theory (DFT) studies. DFT studies suggest that {Cu(II)[Cs-L1-L2]Cl2} have octahedral geometry and +2 oxidation state of Copper is identified on the basis of XPS analysis. The Catalytic behavior of newly prepared heterogeneous catalyst {Cu(II)[Cs-L1-L2]Cl2} was studied for the tetralin oxidation using 70 % tert-butyl hydroperoxide [70 % TBHP]. Tetralin on oxidation gave 1-tetralol, 1-tetralone and some other products. A maximum conversion of 82.11 % tetralin with 10.42 % selectivity of 1-tetralol (T-lol) and 74.89 % selectivity of 1-tetralone (T-lone) was obtained after 5 h of reaction at 80 °C. The heterogeneous catalyst, {Cu(II)[Cs-L1-L2]Cl2}was easy to separate and recyclable. The catalyst was recycled seven times.

Design of Pt@Sn core–shell nanocatalysts for highly selective hydrogenation of cinnamaldehyde to prepare cinnamyl alcohol

The selective hydrogenation of cinnamaldehyde (CAL) to prepare cinnamyl alcohol (COL) is challenging as the unwanted hydrogenation of CC bond in CAL is thermodynamically more favorable than the hydrogenation of CO bond. We herein designed core–shell structured nanoparticles (NPs) that consisted of Pt cores and Sn shells to catalyze the CAL to COL conversion. By simply changing the amount of Sn precursor, we generated Pt@Sn NPs with different Sn shell thickness and catalytic performance. Among the samples, Pt@Sn/SiO2 with Pt/Sn of 1/1 achieved the highest CAL conversion (87.2 %) as well as the COL selectivity (95.4 %), which were 5-fold and 6-fold, respectively, higher than those of Pt/SiO2. This catalyst was also applicable to the hydrogenation of other α, β-unsaturated aldehyde and unsaturated carbonyl compounds. Both experiments and theoretical calculations indicated that the strong Pt-Sn interaction and the partial coverage of Pt by Sn facilitated their adsorption of CO bonds, thus enhancing the conversion of CAL and the selectivity towards COL.

A directed enolization strategy enables by-product-free construction of contiguous stereocentres en route to complex amino acids

Homochiral α-amino acids are widely used in pharmaceutical design as key subunits in chiral catalyst synthesis or as building blocks in synthetic biology. Many synthetic methods have been developed to access rare or unnatural variants by controlling the installation of the α-stereocentre. By contrast, and despite their importance, α-amino acids possessing β-stereocentres are much harder to synthesize. Here we demonstrate an iridium-catalysed protocol that allows the direct upconversion of simple alkenes and glycine derivatives to give β-substituted α-amino acids with exceptional levels of regio- and stereocontrol. Our method exploits the native directing ability of a glycine-derived N–H unit to facilitate Ir-catalysed enolization of the adjacent carbonyl. The resulting stereodefined enolate cross-couples with a styrene or α-olefin to install two contiguous stereocentres. The process offers very high levels of regio- and stereocontrol and occurs with complete atom economy. In broader terms, our reaction design offers a unique directing-group-controlled strategy for the direct stereocontrolled α-alkylation of carbonyl compounds, and provides a powerful approach for the synthesis of challenging contiguous stereocentres.

Are β-Lactones Involved in Carbon-Based Olefination Reactions?

AbstractHeteroatom-based olefinating reagents (e.g., organic phosphonates, sulfonates, etc.) are used to transform carbonyl compounds into alkenes, and their mechanism of action involves aldol-type addition, cyclization, and fragmentation of four-membered ring intermediates. We have developed an analogous process using ethyl 1,1,1,3,3,3-hexafluoroisopropyl methylmalonate, which converts electrophilic aryl aldehydes into α-methylcinnamates in up to 70% yield. The reaction plausibly proceeds through the formation of β-lactone that spontaneously decarboxylates under the reaction conditions. The results shed light on the Knoevenagel–Doebner olefination, for which decarboxylative anti-fragmentation of aldol-type adducts is usually considered.

Synthesis of N-Trifluoromethyl Thiocarbamates and Ureas from 3-Aminopyridine-Derived Carbamates

AbstractThe synthesis of N-trifluoromethyl thiocarbamates and ureas from 3-pyridyl isothiocyanates via the nucleophilic substitution reaction of perfluorophenyl pyridin-3-yl(trifluoromethyl)carbamate is described. Recently, Schoenebeck’s group reported a straightforward method to access N-trifluoromethyl analogues of amides and related carbonyl compounds. However, N-trifluoromethyl thiocarbamates and ureas derived from pyridine-containing amines remain a synthetic challenge. In this paper, the strategy relies on the operationally simple preparation of perfluorophenyl pyridin-3-yl(trifluoromethyl)carbamates, which can smoothly undergo nucleophilic substitution reactions with thiophenol, sodium mercaptide, and amine. Various functional groups such as amide, halogen, ether, and ester were tolerated under these reaction conditions. Notably, alkylamine structures containing pyridine heterocyclic rings are also compatible to access N-trifluoromethyl thiocarbamates.

Characterization and acid treatment of silica and organics in evaporator blowdown wastewater arising from SAGD operations

The evaporator blowdown (EBD) wastewater from high-pressure steam generation for the steam-assisted gravity drainage (SAGD) bitumen extraction process contains elevated concentrations of dissolved inorganic and organic compounds, of which silica and organics pose challenges in its treatment and disposal. This study investigated treatment options for EBD before its disposal. Following detailed physical and chemical characterization of the EBD, we examined its acid treatment with HCl and H2SO4 at pHs ranging from 12 to 2. The acid treatment performance was evaluated in terms of silica and organic removal efficiencies along with the filtration rate and filtrate recovery. Both acids gave similar silica and organic removal efficiencies; however, the filtration performance following the HCl-treatment was better than the H2SO4-treatment. In practice, the acids would likely perform comparably with regard to silica removal and the final process selection would more likely be influenced by other factors such as storage, material compatibility, cost, and downstream or subsurface compatibility. The HCl-treatment was investigated further with both the EBD and prepared silica solutions for the silica removal efficiency and filtration performance. The experiments conducted at ∼20 °C demonstrated higher silica removal efficiencies at pHs 10 and 8, whereas higher organic removal efficiencies were obtained at pHs 4 and 2. The experiments conducted at ∼80 °C showed enhanced silica removal at pH = 8 and higher organic removal at pH = 2. The precipitated solids were characterized using XRD and ATR-FTIR spectroscopy to identify the minerals and functional groups. The XRD patterns demonstrated that the solids generated were amorphous. The ATR-FTIR spectra revealed the predominance of siloxane, silanol, carboxylate and carbonyl compounds. These results confirmed a substantial removal of silica and organic constituents from the EBD through the acid treatment process.

Investigating spectroscopic properties, biological effects, and molecular docking studies of synthesized Schiff base metal complexes

In this current investigation, we have accomplished the synthesis of a Schiff base ligand termed (E)-4-methyl-N′-(2,4,5-trimethoxybenzylidene)benzohydrazide (HL) through a reversible condensation reaction, which engaged a carbonyl compound and a primary amine. This synthesized Schiff base ligand, HL, served as the foundation for the preparation of two metal complexes, namely, M1L (Cu complex) and M2L (La complex). To characterize these compounds, we employed various analytical techniques, including thermogravimetric studies, elemental analysis, powder X-ray diffraction, FT-IR spectroscopy and 1H NMR. The examination of powder X-ray diffraction data provided valuable insights into the crystalline structures of the Cu and La complexes. These shifts are indicative of structural changes in the complexes. Our electronic spectrum analysis revealed the pivotal involvement of the ligand in promoting charge transfer processes, substantiated by an increased concentration of charge transfer transitions observed when the ligand was present. Additionally, we evaluated the antibacterial efficacy of the Schiff base ligand HL and its metal complexes (Cu, La) against a spectrum of bacteria, encompassing both gram-positive (Bacillus subtilis, Enterococcus faecalis) and gram-negative (Escherichia coli) strains. In the current investigation, we utilized molecular docking techniques to explore the interactions between the synthesized HL and its M1L and M2L complexes with protein receptor molecules. These results highlighted the favorable binding energies and stable interactions of these compounds with the protein receptor, M1L displayed notably more stable interactions and lower binding energy compared to M2L. This suggests that M1L may have a stronger potential impact on the free binding energy and molecular interactions.

Ru- and Co-Catalyzed Intermolecular Carbonyl-Alkyne Metathesis Reactions of 1H-Indene-1,2,3-triones with Internal Alkynes.

The catalyst-dependent intermolecular carbonyl-alkyne metathesis (CAM) reaction of 1H-indene-1,2,3-triones with internal alkynes was realized using Ru and Co catalysts. 2-(2-Oxo-1,2-diphenylethylidene)-1H-indene-1,3(2H)-dione derivatives were obtained using a Ru catalyst, whereas S-alkyl 2-(1,3-dioxo-1,3-dihydro-2H-inden-2-ylidene)-2-phenylethanethioates were prepared using a Co catalyst. These transformations led to the synthesis of α,β-unsaturated carbonyl compounds with a broad substrate scope, excellent regiocontrol, and gram-scale amenability. This catalytic strategy using a Co or Ru catalyst has rarely been described for other established CAM catalysts.

Identification of High-School Students’ Conceptual Challenges Related to Alcohols and Carbonyl Compounds by Means of a Four-Tier Diagnostic Test

Identification of High-School Students’ Conceptual Challenges Related to Alcohols and Carbonyl Compounds by Means of a Four-Tier Diagnostic Test

Metabolomics and HS-SPME-GC–MS-based analysis of quality succession patterns and flavor characteristics changes during the fermentation of Lycium barbarum and Polygonatum cyrtonema compound wine

This work set out to investigate how the physicochemical markers, volatiles, and metabolomic characteristics of mixed fermented the fermentation of Lycium barbarum and Polygonatum cyrtonema compound wine (LPCW) from S. cerevisine RW and D. hansenii AS2.45 changed over the course of fermentation. HS-SPME-GC–MS combined with non-targeted metabolomics was used to follow up and monitor the fermentation process of LPCW. In total, 43 volatile chemical substances, mostly alcohols, esters, acids, carbonyl compounds, etc., were discovered in LPCW. After 30 days of fermentation, phenylethyl alcohol had increased to 3045.83 g/mL, giving off a rose-like fresh scent. The biosynthesis of valine, leucine, and isoleucine as well as the metabolism of alanine, aspartic acid, and glutamic acid were the major routes that led to the identification of 1385 non-volatile components in total. This study offers a theoretical foundation for industrial development and advances our knowledge of the fundamental mechanism underlying flavor generation during LPCW fermentation.

Mechanistic insight into the synergistic role of the dual-surfactant system as a green solvent for deoximation reaction: An experimental and computational analysis

Deoximation reaction is one of the most essential transformations in organic synthesis for the precise chemical manufacturing of carbonyl compounds. Developing catalytic deoximation techniques is highly demanding for environmental protection and minimizing expenses in fine chemical operations. Herein, we have reported an environmentally friendly, low-cost, and sustainable approach for regenerating carbonyl compounds from numerous oxime derivatives using microwave irradiation. The method uses I2 and an aqueous solution ofAcacia auriculiformis as the green solvent. The concentration ofAcacia auriculiformiswas discovered to correlate with the percentage production of carbonyl compounds. However, using the dual-surfactant system deliberately improved the regeneration of carbonyl compounds with up to 82% yield at 60:40 ratio. With DFT analysis and quantum chemical parameters, the chemical reactivity and electronic properties of the surfactant systems were determined. Also, the mechanistic interpretation of the actual reaction in the micellar core is depicted, which is well supported by the computational analysis. Overall, our method is green, low-cost, energy-saving, and avoids using toxic reagents and solvents.

Supramolecular Catalysis with Chiral Mono- and Bis-(Thio)Urea-Derivatives

Chiral mono- and bis-(thio)urea supramolecular organocatalysts were studied in the enantioselective vinylogous addition reaction of 2-trimethylsilyloxyfuran (TMSOF) to carbonylic compounds; the corresponding chiral γ-hydroxymethyl-butenolides are obtained in good yields and with high enantiomeric excesses. The catalyst structure, as well as the reaction conditions, strongly influence the efficiency of the reaction. The conformational features of mono(thio)urea catalysts 2 and 3 and bis(thio)urea catalysts 7 and 8 were investigated by DFT calculations along with the structure of their complexes with benzaldehyde. Natural Bond Orbital (NBO) and Non-Covalent Interaction (NCI) calculations provided useful information concerning the activating H-bonding interactions in the complexes.