Aerobic Oxidative Cleavage Research Articles

Non-heme manganese(ii) complex-catalysed oxidative cleavage of 1,2-diols via alcohol-assisted O2 activation

A well-defined, biologically relevant Mn(ii) complex is found to catalyse the aerobic oxidative cleavage of a wide range of diverse 1,2-diols to afford valuable carbonyl compounds and five-membered heterocycles under irradiation of visible light.

Coal Metahydrotacite-B Efficiently Catalyzes the Aerobic Oxidative Cleavage of 1,2-Diols Without Any Additives

Coal Metahydrotacite-B Efficiently Catalyzes the Aerobic Oxidative Cleavage of 1,2-Diols Without Any Additives

The product-controllable aerobic oxidative cleavage of vicinal diols using vanadium-based photocatalysts

A method for the photocatalytic controllable oxidative cleavage of C–C bonds is developed with molecular oxygen as the oxidant.

Amino acid-assisted ferrite/MOF composite formation for visible-light induced photocatalytic cascade C=C aerobic oxidative cleavage functionalization

Due to their high variability and extraordinary features, the MOF-based nanomaterials are regarded as promising photocatalysts in organic reactions. In this study, the magnetic Co-MOF-based nanocomposite (denoted by Cys-CoFe/HK) was prepared through a facile sonochemical method. The composite design was based on the integration and synergy of the desired properties of the components, i.e., optical properties of the magnetic substrate and its separation capability, desirability of metal-organic framework to promote A3-coupling reaction, and use of cysteine ​​amino acid as a natural modifier to modify nanoparticles and make an efficient charge transfer. The information about their structural features was obtained using various characterization methods. In addition to the high photocatalytic activity of the developed composite in the aerobic oxidative propargylic functionalization of styrene under visible light illumination, the composite showed a high capability to interact with a wide range of amines, styrene, and terminal alkynes as participants in A3-coupling reaction. Furthermore, the developed catalyst demonstrated high accessibility of active sites, reusability, and magnetic properties, which accelerated the efficiency of the A3-coupling reaction. Moreover, the mechanistic investigations, including trapping experiments, confirmed the presence of superoxide radical (O2●) and holes (h+) as essential species to perform the considered reaction. Our methodical approach to the fabrication of Cys-CoFe/HK composite provided optimal conditions for improving previous studies and thus the industrial processes in environmentally sensitive areas.

Zn-Nx sites on N-doped carbon for aerobic oxidative cleavage and esterification of C(CO)-C bonds

Selective cleavage of C-C bonds is very important in organic chemistry, but remains challenging because of their inert chemical nature. Herein, we report that Zn/NC-X catalysts, in which Zn2+ coordinate with N species on microporous N-doped carbon (NC) and X denotes the pyrolysis temperature, can effectively catalyze aerobic oxidative cleavage of C(CO)-C bonds and quantitatively convert acetophenone to methyl benzoate with a yield of 99% at 100 °C. The Zn/NC-950 can be applied for a wide scope of acetophenone derivatives as well as more challenging alkyl ketones. Detail mechanistic investigations reveal that the catalytic performance of Zn/NC-950 can be attributed to the coordination between Zn2+ and N species to change the electronic state of the metal, synergetic effect of the Zn single sites with their surrounding N atoms, as well as the microporous structure with the high surface area and structural defects of the NC.

Visible‐Light‐Mediated Aerobic Oxidative C(sp3)−C(sp3) Bond Cleavage of Morpholine Derivatives Using 4CzIPN as a Photocatalyst

AbstractHerein, a metal‐free strategy for the aerobic oxidative cleavage of the inert C(sp3)−C(sp3) bond was developed. Deconstruction of morpholine derivatives was conducted using visible light as an energy source and O2as an oxidant under mild conditions. This procedure demonstrated suitable selectivity and functional group tolerance. Moreover, a possible mechanism involving a radical process was proposed based on a series of mechanism exploration and control experiments.magnified image

Visible Light-Driven, Copper-Catalyzed Aerobic Oxidative Cleavage of Cycloalkanones.

A visible light-driven, copper-catalyzed aerobic oxidative cleavage of cycloalkanones has been presented. A variety of cycloalkanones with varying ring sizes and various α-substituents reacted well to give the distal keto acids or dicarboxylic acids with moderate to good yields.

Cobalt-Catalyzed Aerobic Oxidative Cleavage of Alkyl Aldehydes: Synthesis of Ketones, Esters, Amides, and α-Ketoamides.

A widely applicable approach was developed to synthesize ketones, esters, amides via the oxidative C-C bond cleavage of readily available alkyl aldehydes. Green and abundant molecular oxygen (O2 ) was used as the oxidant, and base metals (cobalt and copper) were used as the catalysts. This strategy can be extended to the one-pot synthesis of ketones from primary alcohols and α-ketoamides from aldehydes.

Copper(I)-catalysed aerobic oxidative selective cleavage of C[sbnd]C bond with DMAP: Facile access to N-substituted benzamides

A base/DMAP system for efficient oxidative cleavage of C(CO)–C(alkyl) bond to generate N-substituted benzamides has been developed in the presence of copper(I) chloride. The usage of inexpensive copper catalyst, broad substrate scope, mild conditions make this protocol very practical. More importantly, this reaction provides an alternative approach for the construction of useful N-substituted benzamides.

A novel selective oxidative cleavage of C[sbnd]C bond mediated by black nickel oxide in the presence of molecular oxygen

A selective aerobic oxidative cleavage of CC bond is developed with black nickel oxide (NiOx) as the catalyst. For the oxidation of 1-phenyl-1, 2-ethanediol, a 97.5% conversion in 96.7% selectivity of benzaldehyde is obtained under 0.3 MPa of O2 at 140 °C for 3 h. The relationship between the catalytic performance of NiOx and structure is discussed. It is concluded that the existence of Ni3+ should be crucial to the activity of catalyst. Moreover, the recycling experiments showed that the catalyst can retain a high activity even after being reused for five times.

Highly efficient and selectivity-controllable aerobic oxidative cleavage of C-C bond over heterogeneous Fe-based catalysts

A base-free selectivity-controllable aerobic oxidative cleavage of C-C bond with heterogeneous Fe-based catalysts (FexOy-N@C3N4) is developed. In the presence of oxygen, 1,2-diols are selectively transformed to the corresponding aldehyde, while the methyl esters are orientedly produced from 1,2-diones in methanol medium.

A computational study of the reaction mechanism of 2,2-azobis(isobutyronitrile)-initiated oxidative cleavage of geminal alkenes.

A computational study of 2,2-azobis(isobutyronitrile) (AIBN)-initiated aerobic oxidative cleavage of alkenes is carried out employing density functional theory (DFT) and high-level coupled-cluster methods, such as coupled-cluster singles and doubles with perturbative triples [CCSD(T)]. Our computations show that the barriers for the formation of dioxetane derivatives suggested by Xu and co-workers (J. Org. Chem., 2014, 79, 7220-7225) for the reaction mechanism of aerobic oxidative cleavage of alkenes are computed to be higher than 65 kcal mol-1. This barrier is relatively high under the reaction conditions. Our results for the Xu mechanism indicate that the reaction does not proceed via the formation of a dioxetane ring under the reaction conditions. Our results demonstrate that the reaction of aerobic oxidative cleavage of geminal alkenes in the presence of AIBN is initiated by the peroxyl radical 9, contrary to the isobutyronitrile radical 2. Our results show that the 2-(2-hydroxyl-1,1-diarylethoxy)-2-methylpropanenitrile radical (15) does not appear throughout the reaction scheme and the reaction progresses over the 2-(2-hydroxyl-2,2-diarylethoxy)-2-methylpropanenitrile radical (13) rather than the 2-(2-hydroxyl-1,1-diarylethoxy)-2-methylpropanenitrile radical (15). Our results are in agreement with the experimental results for the aerobic oxidative cleavage of the geminal disubstituted alkenes. Our results also demonstrate that the epoxide derivatives can be formed as an intermediate under the reaction conditions. This reaction is not applicable for pyridine derivatives due to the conversion of vinylpyridine derivatives to N-oxide derivatives.

Alternative ball-milling synthesis of vanadium-substituted polyoxometalates as catalysts for the aerobic cleavage of C-C and C-O bonds.

Vanadium-substituted phosphomolybdic acids (H3+x[PMo12-xVxO40], denoted as Vx) are well-known oxidation catalysts that are generally prepared by the hydrothermal treatment of MoO3 and V2O5 in the presence of H3PO4. This synthesis procedure is highly energy consuming and the Vx yields are not always acceptable. In the present work, an alternative hybrid mechanochemical/hydrothermal synthesis of Vx is proposed, comprising the ball-milling of MoO3 and V2O5, followed by a hydrothermal attack. The resulting materials, with 2 ≤ x ≤ 3, obtained from this new route were compared, in terms of yield, energy consumption and catalytic activity, with a reference V3 sample prepared through a conventional hydrothermal treatment. The ball-milling step proved to lead not only to a shorter and far more energy-saving synthesis procedure, but also to high yields of Vx. Moreover, Vx from this alternative route proved to be generally more active than the conventionally prepared V3 in the aerobic oxidative cleavage of C-O and C-C bonds in 2-phenoxyacetophenone, used herein as a lignin model compound.

Aerobic oxidative cleavage of C[dbnd]C bond to carbonyl compound

A highly efficient and selective carbon–carbon double bonds cleavage of styrene compounds involving molecular oxygen was achieved using TBHP as a free radical initiator in diethylene glycol diethyl ether medium. Various styrene compounds, such as phenyl acrylic acids and its esters, 2-substituted 3-phenyl acrylic acids and its esters, chalcones, 4-phenyl-3-buten-2-one and bis(2-phenylvinyl) ketone, 5-benzylidene-1,3-dimethyl-pyrimidine-2,4,6-triones, could be effectively oxidized into the corresponding aryl carbonyl compounds, and the yield was up to 99%. A suitable mechanism was proposed. Gram-level synthesis further illustrated the practicality of our method.

Na-MnOx catalyzed aerobic oxidative cleavage of biomass-derived 1,2-diols to synthesis medium-chain furanic chemicals

Medium-chain furanic chemicals have outstanding practical potential, especially in the application of pharmaceuticals and polymers. Herein, we describe an eco-friendly and efficient heterogeneous sodium-doped porous sodium manganese oxide catalyst (Na-MnOx) for oxidative cleavage of furanic 1,2-diols into medium-chain furanic aldehyde compounds. Subsequently, various high value-added chemicals (diacids and esters, diols, hydroxy acids, acrylics) were synthesized based on the widely applicable and highly selective catalytic approaches. The Na-MnOx was prepared by the coprecipitation method and characterized by XRD, SEM, XPS and FT-IR, and TGA. XPS revealed that Mn species existed in the mixed oxidation states MnII, MnIII and MnIV. When NaOH concentration up to 1.8 mol L−1 during the preparation process of the catalyst, the ratio of Mn4+ in the catalyst was the highest, and the yield of product (Furan-2-acrolein) in the model reaction is also optimal. Overall, this protocol developed a novel and general route for the preparation of medium-chain furanic compounds utilizing cellulose-derived platform molecules.

Aerobic Oxidative Cleavage and Esterification of C(OH)–C Bonds

Summary C(OH)–C bonds are widely distributed in naturally renewable biomass, such as carbohydrates, lignin, and their platform molecules. Selective cleavage and functionalization of C(OH)–C bonds is an attractive strategy in terms of producing value-added chemicals from biomass. However, effective transformation of alcohols into esters by activation of C(OH)–C bonds has not been achieved so far. Herein, for the first time, we report selective cleavage and esterification of C(OH)–C bonds, catalyzed by inexpensive copper salts, using environmentally benign oxygen as the oxidant, to afford methyl esters in excellent yields. A diverse range of phenylethanol derivatives that contain C(OH)–C bonds were effectively converted into methyl benzoates. Detailed analysis revealed that the high efficiency and selectivity resulted mainly from the fact that, in addition to the major esterification reaction, the side products (e.g., olefins and acids) were also transformed in situ into esters in the reaction system.

Iodine‐Catalyzed Aerobic Oxidative Cleavage of C–C δ‐Bonds: Difunctionalization of Dienones

A new and efficient catalytic strategy that combines organocatalysis and iodine catalysis was first developed for the difunctionalization of dienone. The reaction proceeds under metal‐free conditions and employs dioxygen from air as the mild oxidant. The approach results in 1,5‐diketo epoxides in moderate to high yields.

Metal-free Photocatalytic Aerobic Oxidative Cleavage of C-C Bonds in 1,2-Diols.

The preparation of carbonyl compounds by the aerobic oxidative cleavage of C-C bonds in 1,2-diols under mild reaction conditions is a very significant reaction and is widely employed in various scenarios. Avoiding the use of harmful stoichiometric oxidants and adopting a greener chemical process remain a challenge for this reaction to date. In this manuscript, a heterogeneous metal-free photocatalytic strategy without any additive was developed for aerobic oxidative cleavage of C-C bonds in 1,2-diols at ambient conditions with visible light. The reaction mechanism was further studied through a series of control experiments and density functional theory (DFT) calculations. In addition, the catalytic system showed a broad substrates scope, including aliphatic (linear or cyclic) 1,2-diols, benzylic, alkenyl 1,2-diols, and α-hydroxy acids (such as lactic acid). Thus, this strategy could serve as a method for the transformation of 1,2-diols to corresponding carbonyl compounds by the aerobic oxidative cleavage of C-C bonds.

Aerobic Oxidative Cleavage of Vicinal Diol Fatty Esters by a Supported Ruthenium Hydroxide Catalyst

Oxidative cleavage of fatty acids and fatty acid derivatives can be used to obtained mono- and dicarboxylic acids, which are valuable building blocks in different industries. Although ozonolysis ha...

Computational Study for the Reaction Mechanism of N-Hydroxyphthalimide-Catalyzed Oxidative Cleavage of Alkenes.

A computational study of N-hydroxyphthalimide-catalyzed aerobic oxidative cleavage of alkenes is carried out employing density functional theory and high-level coupled-cluster methods, such as coupled-cluster singles and doubles with perturbative triples [CCSD(T)]. Our results demonstrate that the reaction proceeds through the alkoxyl radicals, as opposed to the mechanism suggested by Jiao and co-workers (Org. Lett. 2012, 14, 4158-4161), in which the reaction proceeds via formation of the dioxetane ring. The barriers for the formation of dioxetane derivatives are computed to be higher than 50 kcal mol-1, while the barriers for the formation of alkoxyl radicals are as low as 13 kcal mol-1. Our results also demonstrate that epoxide derivatives can be formed as intermediates or byproducts under the reaction conditions.