18181-71-0Relevant articles and documents
Multiple Mechanisms Mapped in Aryl Alkyl Ether Cleavage via Aqueous Electrocatalytic Hydrogenation over Skeletal Nickel
Hegg, Eric L.,Jackson, James E.,Klinger, Grace E.,Saffron, Christopher M.,Zhou, Yuting
supporting information, p. 4037 - 4050 (2020/03/10)
We present here detailed mechanistic studies of electrocatalytic hydrogenation (ECH) in aqueous solution over skeletal nickel cathodes to probe the various paths of reductive catalytic C-O bond cleavage among functionalized aryl ethers relevant to energy science. Heterogeneous catalytic hydrogenolysis of aryl ethers is important both in hydrodeoxygenation of fossil fuels and in upgrading of lignin from biomass. The presence or absence of simple functionalities such as carbonyl, hydroxyl, methyl, or methoxyl groups is known to cause dramatic shifts in reactivity and cleavage selectivity between sp3 C-O and sp2 C-O bonds. Specifically, reported hydrogenolysis studies with Ni and other catalysts have hinted at different cleavage mechanisms for the C-O ether bonds in α-keto and α-hydroxy β-O-4 type aryl ether linkages of lignin. Our new rate, selectivity, and isotopic labeling results from ECH reactions confirm that these aryl ethers undergo C-O cleavage via distinct paths. For the simple 2-phenoxy-1-phenylethane or its alcohol congener, 2-phenoxy-1-phenylethanol, the benzylic site is activated via Ni C-H insertion, followed by beta elimination of the phenoxide leaving group. But in the case of the ketone, 2-phenoxyacetophenone, the polarized carbonyl πsystem apparently binds directly with the electron rich Ni cathode surface without breaking the aromaticity of the neighboring phenyl ring, leading to rapid cleavage. Substituent steric and electronic perturbations across a broad range of β-O-4 type ethers create a hierarchy of cleavage rates that supports these mechanistic ideas while offering guidance to allow rational design of the catalytic method. On the basis of the new insights, the usage of cosolvent acetone is shown to enable control of product selectivity.
Cleavage of CC and Co bonds in β-O-4 linkage of lignin model compound by cyclopentadienone group 8 and 9 metal complexes
Kishino, Masamichi,Kusumoto, Shuhei,Nozaki, Kyoko
supporting information, p. 477 - 480 (2020/05/19)
Degradation of 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphe-noxy)propane-1,3-diol (1), a model compound for lignin β-O-4 linkage was examined with iron, ruthenium, rhodium and iridium complexes bearing cyclopentadienone ligand. Cyclopentadienone iron complex gave only a small amount of degraded product with reduced molecular weight. Cyclopentadienone ruthenium complex, so called Shvo's catalyst, afforded 3,4-dimethoxybenzaldehyde (a3) in 14.3% yield after CαCβ bond cleavage. On the other hand, cyclopentadienone group-9 metal complexes catalyzed CβO bond cleavage to afford guaiacol (b1) as a main product in up to 74.9% yield.
Method for depolymerizing lignin into aromatic compound through photocatalysis (by machine translation)
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Paragraph 0047-0052, (2019/07/29)
The invention relates to a method, for depolymerizing lignin into an aromatic compound by photocatalysis. Belong to application chemistry technical field. The method uses lignin as a reaction substrate, and under the excitation of a light source, under the catalysis of a light source, the C-C bond is selectively cracked under the assistance of a base and a hydrogen donor, and the molar ratio of the reaction substrate, photocatalyst, base, and hydrogen donor is 100: (0.5~10) 1~20: (1~20), and the reaction temperature is room temperature, and the reaction substrate is a reaction substrate. The reaction time was 6~24 hours. The method has the advantages, such as simple reaction steps, mild reaction conditions, high bond breaking selectivity 100%, high yield, atom efficiency, environmental protection and the like, has the functions, is high in selectivity, and efficiently degrades the lignin, and is beneficial to large-scale industrial production and application of lignin degradation and the like. (by machine translation)
Revisiting Hydroxyalkylation of Phenols with Cyclic Carbonates
Kao, Shih-Chieh,Lin, Yi-Ching,Ryu, Ilhyong,Wu, Yen-Ku
supporting information, p. 3639 - 3644 (2019/07/10)
Described is a tetrabutylammonium fluoride-mediated hydroxyalkylation reaction of phenols with cyclic carbonates. This operationally simple method enables the synthesis of a variety of aryl β-hydroxyethyl ethers in good to excellent yields with a very small amount of catalyst loading (0.1–1 mol%). Of particular note is the efficient conversion of aromatic diols and phloroglucinol to the corresponding bis- and tris-hydroxyethylated products. To further showcase the versatility of this protocol, guaifenesin was prepared with a single step by the condensation of guaiacol and glycerol carbonate. We also developed a flow ethoxylation process permitting the continuous synthesis of multiflorol. (Figure presented.).
Preparation method for 2-(2-methoxyphenoxy)ethylamine
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Paragraph 0014, (2019/01/24)
The invention provides a preparation method for 2-(2-methoxyphenoxy)ethylamine. The preparation method comprises the following steps: synthesizing 2-(2-methoxyphenoxy)ethanol with guaiacol as a starting material; then synthesizing 2-(2-methoxyphenoxy)chloroethane through chlorination; then reacting 2-(2-methoxyphenoxy)chloroethane with potassium phthalimide to obtain N-(o-methoxyphenoxyethyl)-phthalimide; and finally, performing basic hydrolysis to obtain 2-(2-methoxyphenoxy)ethylamine. The yields of the above four steps of reactions are that the yield of 2-(2-methoxyphenoxy)ethanol is 98.9%;the yield of 2-(2-methoxyphenoxy)chloroethane is 93.7%; the yield of N-(o-methoxyphenoxyethyl)-phthalimide is 86.4%; the yield of 2-(2-methoxyphenoxy)ethylamine is 91.2%; and the total yield of the four steps is 73.04%, which is higher than the yield of 43% in conventional production processes. The preparation method of the invention reduces the production cost of 2-(2-methoxyphenoxy)ethylamine and is safe in the production process.
A Redox Strategy for Light-Driven, Out-of-Equilibrium Isomerizations and Application to Catalytic C-C Bond Cleavage Reactions
Ota, Eisuke,Wang, Huaiju,Frye, Nils Lennart,Knowles, Robert R.
supporting information, p. 1457 - 1462 (2019/01/25)
We report a general protocol for the light-driven isomerization of cyclic aliphatic alcohols to linear carbonyl compounds. These reactions proceed via proton-coupled electron-transfer activation of alcohol O-H bonds followed by subsequent C-C β-scission of the resulting alkoxy radical intermediates. In many cases, these redox-neutral isomerizations proceed in opposition to a significant energetic gradient, yielding products that are less thermodynamically stable than the starting materials. A mechanism is presented to rationalize this out-of-equilibrium behavior that may serve as a model for the design of other contrathermodynamic transformations driven by excited-state redox events.
Iridium-catalysed primary alcohol oxidation and hydrogen shuttling for the depolymerisation of lignin
Lancefield, Christopher S.,Teunissen, Lucas W.,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
supporting information, p. 3214 - 3221 (2018/07/31)
Lignin is a potentially abundant renewable resource for the production of aromatic chemicals, however its selective depolymerisation is challenging. Here, we report a new catalytic system for the depolymerisation of lignin to novel, non-phenolic monoaromatic products based on the selective β-O-4 primary alcohol dehydrogenation with a Cp?Ir-bipyridonate catalyst complex under basic conditions. We show that this system is capable of promoting the depolymerisation of model compounds and isolated lignins via a sequence of selective primary alcohol dehydrogenation, retro-aldol (Cα-Cβ) bond cleavage and in situ stabilisation of the aldehyde products by transfer (de)hydrogenation to alcohols and carboxylic acids. This method was found to give good to excellent yields of cleavage products with both etherified and free-phenolic lignin model compounds and could be applied to real lignin to generate a range of novel non-phenolic monomers including diols and di-acids. We additionally show, by using the same catalyst in a convergent, one-pot procedure, that these products can be selectively channelled towards a single di-acid product, giving much simpler product mixtures as a result.
Formononetin derivatives and preparation methods and medical application thereof
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Paragraph 0123; 0124; 0125; 0126; 0127; 0128, (2017/04/29)
The invention relates to the field of pharmaceutical chemistry, and relates to formononetin derivatives and preparation methods and medical application thereof, in particular to formononetin derivatives with the general formula as shown in (I), preparation methods thereof, pharmaceutical compositions containing the compounds and medical application of the derivatives and the pharmaceutical compositions, particularly, application of the derivatives and the pharmaceutical compositions serving as drugs for preventing or treating hyperlipidaemia or obesity or type-II diabetes. Please see the formula in the description.
Structure-guided development of dual β2 adrenergic/dopamine D2 receptor agonists
Weichert, Dietmar,Stanek, Markus,Hübner, Harald,Gmeiner, Peter
, p. 2641 - 2653 (2016/06/08)
Aiming to discover dual-acting β2 adrenergic/dopamine D2 receptor ligands, a structure-guided approach for the evolution of GPCR agonists that address multiple targets was elaborated. Starting from GPCR crystal structures, we describ
SELECTIVE CARBON-CARBON BOND CLEAVAGE BY EARTH ABUNDANT VANADIUM COMPOUNDS UNDER VISIBLE LIGHT PHOTOCATALYSIS
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Page/Page column 35, (2016/09/22)
Provided herein a vanadium(V) complex of formula I, where R1 to R8 are as defined herein. Also provided herein are reactions making use of the vanadium(V) complex of formula I, such as selective sp3-sp3 carbon-carbon bond cleavage under visible light photocatalysis and photodegradation of lignin.
