Ketone Carbonyl Group Research Articles

Samarium Diiodide/Samarium-Mediated Deoxygenative Hydrosilylation of Ketones.

The first deoxygenative hydrosilylation of ketones promoted by samarium diiodide and samarium has been reported. In this approach, secondary alkyl silanes are synthesized from unactivated ketones and chlorosilanes in one step. The carbonyl group of ketones is activated by SmI2-mediated single-electron transfer process, which follows a deoxygenative elimination of O=Sm. Broad substrate scope and excellent functional group tolerance has been demonstrated.

Non-Ionic Peterson-Type Olefination Reactivity and its Use in a Silicon-Promoted Carbonyl-Carbonyl Cross Coupling Reaction.

The [2+2] cycloaddition reaction between the Si=C double bond of adamantylsilene and the carbonyl group of aliphatic, aromatic or acetylenic ketones and aldehydes is demonstrated. The product of this reaction that is central to a non-ionic version of the Peterson olefination is an unusual four-membered 1,2-silaoxetane heterocycle that was characterized spectroscopically and crystallographically. In the presence of SiO2, the silaoxetane undergoes retro-cycloaddition with the formation of alkene products. As the [2+2] cycloaddition proceeds without the necessity of any base, enolizable ketones can be converted into olefins. In addition, it is shown that the adamantylsilene can be produced in situ by a sila-Peterson reaction, providing valuable input for the development of a new one-pot silicon-based reductive carbonyl-carbonyl cross coupling methodology.

Non‐Ionic Peterson‐Type Olefination Reactivity and its Use in a Silicon‐Promoted Carbonyl‐Carbonyl Cross Coupling Reaction

AbstractThe [2+2] cycloaddition reaction between the Si=C double bond of adamantylsilene and the carbonyl group of aliphatic, aromatic or acetylenic ketones and aldehydes is demonstrated. The product of this reaction that is central to a non‐ionic version of the Peterson olefination is an unusual four‐membered 1,2‐silaoxetane heterocycle that was characterized spectroscopically and crystallographically. In the presence of SiO2, the silaoxetane undergoes retro‐cycloaddition with the formation of alkene products. As the [2+2] cycloaddition proceeds without the necessity of any base, enolizable ketones can be converted into olefins. In addition, it is shown that the adamantylsilene can be produced in situ by a sila‐Peterson reaction, providing valuable input for the development of a new one‐pot silicon‐based reductive carbonyl‐carbonyl cross coupling methodology.

Theoretical Analysis of Selectivity Differences in Ketoreductases toward Aldehyde and Ketone Carbonyl Groups.

Lactobacillus kefir alcohol dehydrogenase (LkADH) and ketoreductase from Chryseobacterium sp. CA49 (ChKRED12) exhibit different chemoselectivity and stereoselectivity toward a substrate with both keto and aldehyde carbonyl groups. LkADH selectively reduces the keto carbonyl group while retaining the aldehyde carbonyl group, producing optically pure R-alcohols. In contrast, ChKRED12 selectively reduces the aldehyde group and exhibits low reactivity toward ketone carbonyls. This study investigated the structural basis for these differences and the role of specific residues in the active site. Molecular dynamics (MD) simulations and quantum chemical calculations were used to investigate the interactions between the substrate and the enzymes and the essential cause of this phenomenon. The present study has revealed that LkADH and ChKRED12 exhibit significant differences in the structure of their respective active pockets, which is a crucial determinant of their distinct chemoselectivity toward the same substrate. Moreover, residues N89, N113, and E144 within LkADH as well as Q151 and D190 within ChKRED12 have been identified as key contributors to substrate stabilization within the active pocket through electrostatic interactions and van der Waals forces, followed by hydride transfer utilizing the coenzyme NADPH. Furthermore, the enantioselectivity mechanism of LkADH has been elucidated using quantum chemical methods. Overall, these findings not only provide fundamental insights into the underlying reasons for the observed differences in selectivity but also offer a detailed mechanistic understanding of the catalytic reaction.

In Situ S-Doping Engineering for Highly Efficient NH3-SCR over Metal-Free Carbon Catalysts: A Novel Synergetic Promotional Mechanism.

Cyclic desulfurization-regeneration-denitrification based on metal-free carbon materials is one of the most promising ways to remove NOx and SO2 simultaneously. However, the impact of S-doping induced by the cyclic desulfurization and regeneration (C-S-R) process on the selective catalytic reduction (SCR) is not well understood. Herein, it is demonstrated that the C-S-R process at 500 °C induces in situ S-doping with a significant accumulation of C-S-C structures. NOx conversion was dramatically enhanced from 18.95% of the original sample to 84.55% of the S-doped sample. Density functional theory calculations revealed that the C-S-C structure significantly regulates the electronic structure of the C atom adjacent to the ketonic carbonyl group, thereby significantly altering the NH3 adsorption configuration with superior adsorption capacity. Moreover, S-doping induces an extra electron transfer between the N atom of the NH3 molecule and the C atom of the carbon plane, thereby promoting the activation of NH3 over the ketonic carbonyl group with a reduced energy barrier. This study elucidates a synergetic promotional mechanism between the ketonic carbonyl group and the C-S-C structure for SCR, offering a novel design strategy for high-performance heteroatom-doped carbon catalysts in industrial applications.

Alternative Approach to Access 5-Hydroxy-1H-pyrrol-2-(5H)-ones from Base-Induced Tandem Intramolecular Cyclization of Sulfur Ylide with Ketones and 1,3-Hydroxy Rearrangement.

An easily adaptable protocol for the preparation of 5-hydroxy-1H-pyrrol-2(5H)-ones from readily available starting materials has been reported. The reaction of sulfur ylides with carbonyl compounds is a common approach to synthesizing epoxides. Alternatively, we have developed a method with mild reaction conditions wherein sulfur ylide underwent an intramolecular cyclization with a ketonic carbonyl group in a highly efficient way and was followed by 1,3-hydroxy rearrangement to produce 5-hydroxy-1H-pyrrol-2(5H)-ones in excellent yields. The present method offers a straightforward approach to synthesize 5-hydroxy-1H-pyrrol-2(5H)-ones from sulfur ylides without the aid of transition metal in one-pot operation, which involves sequential cyclization and rearrangement reaction. The formation of 5-hydroxy-1H-pyrrol-2(5H)-ones is supported by different spectroscopic techniques, including X-ray crystallographic data and 2D NMR studies (COSY, HSQC, HMBC, and DEPT).

Open-Cage Fullerene as a Macrocyclic Ligand for Na, Pt, and Rh Metal Complexes.

An open-cage [60]fullerene derivative was prepared through Malaprade oxidation of a vicinal triol moiety as the key step. Above the 17-membered orifice, there is one carboxyl group. Three ketone carbonyl groups and one lactone carbonyl group are located on the rim of the orifice. The carboxylic and carbonyl oxygen atoms around the orifice act as strong polydentate ligands for a sodium ion. These oxygen atoms also react with [Rh(CO)2Cl]2 to form various isomeric rhodium complexes with comparable stability. The fullerene C═C bond on the rim of the orifice forms a stable platinum complex when treated with Pt(PPh3)4. Single crystal X-ray diffraction data reveal that one of the carboxylic oxygen atoms above the orifice forms a H-bond with the water molecule trapped in the cage.

1,3-Diamine-Derived Catalysts: Design, Synthesis, and the Use in Enantioselective Mannich Reactions of Ketones.

1,3-Diamine-derived catalysts were designed, synthesized, and used in asymmetric Mannich reactions of ketones. The reactions catalyzed by one of the 1,3-diamine derivatives in the presence of acids afforded the Mannich products with high enantioselectivities under mild conditions. In most cases, bond formation occurred at the less-substituted α-position of the ketone carbonyl group. Our results indicate that the primary and the tertiary amines of the 1,3-diamine derivative cooperatively act for the catalysis.

Polyketides with Anti-Inflammatory Activity from Trichoderma koningiopsis, a Rhizosphere Fungus from the Medicinal Plant Polygonum paleaceum.

Twelve new fungal polyketides, koningiopisins I-P (1-8) and trichoketides C-F (9-12), together with six known congeners (13-18), were isolated from Trichoderma koningiopsis, a rhizosphere fungus obtained from the medicinal plant Polygonum paleaceum. Their structures and absolute configurations were established by spectroscopic analysis, single-crystal X-ray diffraction, the modified Mosher's method, chemical derivatization, the octant rule, and 13C NMR and ECD calculations. Compounds 1-5 are tricyclic polyketides possessing an octahydrochromene framework with a 6,8-dioxabicyclo[3.2.1]octane core. Compounds 7 and 8 contain a unique ketone carbonyl group at C-7 and differ from other members of this group of compounds with the ketone carbonyl group at C-1. Compounds 1, 2, and 13 showed inhibitory activity on LPS-induced BV-2 cells on NO production with IC50 values of 14 ± 1, 3.0 ± 0.5, and 8.9 ± 2.7 μM, respectively.

Ambient Pressure Ir@Hal-Catalyzed Hydrogenation of Aryl Aldehydes, Ketones, and Phenol.

A reliable method for encapsulation of iridium nanoparticles (6-8 nm particles) in halloysite Ir@Hal has been developed. The Ir@Hal nanocomposite was found to be a highly efficient catalyst for the hydrogenation and transfer hydrogenation of the carbonyl group of aryl aldehydes, aryl ketones, and aliphatic ketones to afford alcohols in high yields. In addition, phenol could be hydrogenated to furnish cyclohexanol (93-95% yield) at ambient pressure at 50 °C. Further, the catalyst was easily recovered and recycled without significant loss of catalytic activity over multiple trials.

The role of primary amines in modified chitosan to enhance the aldol condensation of biomass-derived carbonyl compounds

Aldol condensation is a key step for converting the lignocellulosic platform compounds to fuel. The catalyst used in the aldol condensation requires the avoidance of the overactivation of aldehyde groups while fully activating ketone carbonyl groups. Herein, the modified chitosan (NaOH/CT-0.6) was applied for the efficient syntheses of single condensation product from biomass-derived furfural (FFR) and methyl isobutyl ketone (MIBK), achieving an 87.01% yield of C11 at 60 °C and 3 h. Catalyst characterization revealed that the exposure of –NH2 groups in chitosan after modification led to the formation of the imine with the CO groups of FFR. It was confirmed that the imine formation avoided the overactivation of aldehyde groups and improved cross-condensation product yield. Furthermore, the theoretical feasibility of the imine catalytic path was elucidated through DFT simulation and in situ DRIFTS analysis. Finally, the obtained condensation products were subjected to hydrodeoxygenation (HDO) over the 2 wt% Pd/Nb2O5, obtaining the hydrocarbon components suitable for bio-jet fuels. This work contributes significantly to the design of novel catalysts for aldol condensation reactions and the efficient conversion of biomass.

Identification of endogenous carbonyl steroids in human serum by chemical derivatization, hydrogen/deuterium exchange mass spectrometry and the quantitative structure-retention relationship

Steroids are tetracyclic aliphatic compounds, and most of them contain carbonyl groups. The disordered homeostasis of steroids is closely related to the occurrence and progression of various diseases. Due to high structural similarity, low concentrations in vivo, poor ionization efficiency, and interference from endogenous substances, it is very challenging to comprehensively and unambiguously identify endogenous steroids in biological matrix. Herein, an integrated strategy was developed for the characterization of endogenous steroids in serum based on chemical derivatization, ultra-performance liquid chromatography quadrupole Exactive mass spectrometry (UPLC-Q-Exactive-MS/MS), hydrogen/deuterium (H/D) exchange, and a quantitative structure-retention relationship (QSRR) model. To enhance the mass spectrometry (MS) response of carbonyl steroids, the ketonic carbonyl group was derivatized by Girard T (GT). Firstly, the fragmentation rules of derivatized carbonyl steroid standards by GT were summarized. Then, carbonyl steroids in serum were derivatized by GT and identified based on the fragmentation rules or by comparing retention time and MS/MS spectra with those of standards. H/D exchange MS was utilized to distinguish derivatized steroid isomers for the first time. Finally, a QSRR model was constructed to predict the retention time of the unknown steroid derivatives. With this strategy, 93 carbonyl steroids were identified from human serum, and 30 of them were determined to be dicarbonyl steroids by the charge number of characteristic ions and the number of exchangeable hrdrogen or comparing with standards. The QSRR model built by the machine learning algorithms has an excellent regression correlation, thus the accurate structures of 14 carbonyl steroids were determined, among which three steroids were reported for the first time in human serum. This study provides a new analytical method for the comprehensive and reliable identification of carbonyl steroids in biological matrix.

Feasibility analysis of clean utilization of kitchen waste oil and lignite by co-fermentation treatment

In order to improve the efficiency of biomethane production through lignite anaerobic fermentation and perform the treatment and application of kitchen waste oil (KWO), different KWO to lignite ratios were used for combined anaerobic fermentation of biomethane. Biogas production characteristics, fermentation broth, and solid residue utilization properties of co-fermentation were analyzed using liquid fatty acid, thermogravimetric (TG), and combustion flue gas tests. The experimental results show that the co-anaerobic fermentation of KWO and lignite can improve the biogenic methane production, and the ratio of the two will also affect the biogenic methane production. Among them, the biogenic methane production by the co-anaerobic fermentation of 1.2 g KWO and 20 g of lignite is the largest, which is 377.86% higher than that by the anaerobic fermentation of single lignite. According to the three-dimensional fluorescence spectrum analysis, the fermentation substrate with the highest biogenic methane production contains more fulvic acid, tryptophan, lysine, phenol hydroxyl, ketone carbonyl, carbonyl, and other groups. In the change of fatty acid content before and after anaerobic fermentation, the content of palmitic acid, stearic acid, oleic acid, and other non-degradable fatty acids contained in KWO significantly decreased, and the volatile fatty acids significantly increased. After anaerobic fermentation, the volatilization analysis temperature, ignition point, and combustion temperature of residual coal are advanced, and the combustion is more stable. At the same time, the emission of combustion pollution gas of residual coal after fermentation is significantly reduced, which is conducive to the clean utilization of lignite.

Identification of Active Sites over Metal-Free Carbon Catalysts for Flue Gas Desulfurization.

Carbon-based catalysts have been extensively used for flue gas desulfurization (FGD) and have exerted great importance in controlling SO2 emissions over the past decades. However, many fundamental details about the nature of the active sites and desulfurization mechanism still remain unclear. Here, we reported the experimental and theoretical identifications of active sites in FGD on carbon catalysts. Temperature-programmed decomposition allowed us to modulate the number of oxygen functional groups on carbon catalysts and to establish its correlation with desulfurization activity. Selective passivation further demonstrated that the ketonic carbonyl (C═O) groups are the intrinsic active sites for FGD reaction. Combined with transient response experiments, quasi-in situ X-ray photoelectron spectroscopy, and density functional theory simulations, it was revealed that desulfurization reaction on carbon catalysts mainly proceeded via the Langmuir-Hinshelwood mechanism, during which the nucleophilic ketonic C═O groups served as active sites for chemically absorbing SO2 and their adjacent sp2-hybridized carbon atoms dissociatively activated O2. It also turned out that the formation of H2SO4 is the reaction barrier step. The output of this study should not only advance the understanding of desulfurization at the atomic scale but also provide a general guideline for the rational design of efficient carbon catalysts for FGD.

Electrochemical deoxygenative arylation of aldehydes and ketones.

The construction of diaryl alkanes from aromatic aldehydes or ketones with electron-deficient arenes is achieved in the presence of trivalent phosphine under electrochemical conditions. Reductive coupling between electron-deficient arenes and the carbonyl groups of aldehydes or ketones occurs at the cathode to yield diaryl alcohols. At the anode, the trivalent phosphine reagent may undergo single-electron oxidation to generate its radical cation, which reacts with the diaryl alcohols to form dehydroxylated products.

An oxygen-assisted conversion of butanol to value-added products on nanocarbon catalysts: tuning product selectivity via nitrogen doping

The activity and mechanistic and kinetic analysis of nB conversion on NCNT were investigated, and the high ODH activity stems from the donated electrons from nitrogen to ketonic carbonyl groups.

Aryl Annulation: A Powerful Simplifying Retrosynthetic Disconnection.

Retrosynthetic deconstruction of a core aromatic ring is an especially simplifying retrosynthetic step, reducing the complexity of the precursor synthetic target. Moreover, when implemented to provide a penultimate intermediate, it enables late-stage divergent aryl introductions, permitting deep-seated core aryl modifications ordinarily accessible only by independent synthesis. Herein, we highlight the use of a ketone carbonyl group as the functionality to direct such late-stage divergent aryl introductions onto a penultimate intermediate with a projected application in the total synthesis of vinblastine and its presently inaccessible analogs containing indole replacements. Although the studies highlight this presently unconventional strategy with an especially challenging target in mind, the increase in molecular complexity (intricacy) established by the synthetic implementation of the powerful retrosynthetic disconnection, the use of a ketone as the precursor enabling functionality, and with adoption of either conventional or new wave (hetero)aromatic annulations combine to define a general and powerful strategy suited for wide-spread implementation with near limitless scope in target diversification.

A Stereodivergent–Convergent Chiral Induction Mode in Atroposelective Access to Biaryls via Rhodium-Catalyzed C–H Bond Activation

Understanding the reaction mechanisms, particularly the chiral induction mode, is critical for the development of new asymmetric catalytic reactions. Rhodium(III)-catalyzed C–H activation en route to atroposelective [4 + 2] annulative coupling with α-diazo β-ketoesters has been realized, affording axially chiral phenanthrenes in good to excellent enantioselectivity. A combination of experimental and computational studies revealed a nontraditional stereodivergent–convergent chiral induction mode. The reaction proceeded with a rhodafluorene intermediate, followed by competitive, constructive, and stereodivergent migratory insertions of the two Rh–C(aryl) bonds into the carbene species to give β-ketoester intermediates. Then, the other Rh–C(aryl) bond migratorily inserts into the ketone carbonyl group. Following this stereodetermining carbonyl insertion, an ester-chelated rhodium(III) alkoxide species bearing two poorly controlled chiral centers and a well-controlled C(sp2)–C(sp3) chiral axis is generated. The final product is delivered via stereoconvergent elimination of a rhodium(III) species with retention of the well-controlled axial chirality and with loss of the central chirality.

Rational design of metabolically stable HDAC inhibitors: An overhaul of trifluoromethyl ketones

Epigenetic regulation of gene expression using histone deacetylase (HDAC) inhibitors is a promising strategy for developing new anticancer agents. The most common HDAC inhibitors are hydroxamates, which, though highly potent, have limitations due to their poor pharmacokinetic properties and lack of isoform selectivity. Trifluoromethylketones (TFMK) developed as alternatives to hydroxamates are rapidly metabolized to inactive trifluoromethyl alcohols in vivo, which prevented their further development as potential drug candidates. In order to overcome this limitation, we designed trifluoropyruvamides (TFPAs) as TFMK surrogates. The presence of an additional electron withdrawing group next to the ketone carbonyl group made the hydrate form of the ketone more stable, thus preventing its metabolic reduction to alcohol in vivo. In addition, this structural modification reduces the potential of the TFMK group to act as a covalent warhead to eliminate off-target effects. Additional structural changes in the cap group of the inhibitors gave analogues with IC50 values ranging from upper nanomolar to low micromolar in the cytotoxicity assay, and they were more selective for cancer cells over normal cells. Some of the most active analogues inhibited HDAC enzymes with low nanomolar IC50 values and were found to be more selective for HDAC8 over other isoforms. These molecules provide a new class of HDAC inhibitors with a metabolically stable metal-binding group that could be used to develop selective HDAC inhibitors by further structural modification.

Study of the Equilibrium of Heterophase Reactions in the Gas–Liquid System Using Hydrogenation of the Carbonyl Group in Ketones

Study of the Equilibrium of Heterophase Reactions in the Gas–Liquid System Using Hydrogenation of the Carbonyl Group in Ketones