123-11-5Relevant articles and documents
CuII-salan compounds: Synthesis, characterization and evaluation of their potential as oxidation catalysts
Ad?o, Pedro,Barroso, Sónia,Avecilla, Fernando,Oliveira, M. Concei??o,Pessoa, Jo?o Costa
, p. 212 - 223 (2014)
We report the synthesis and characterization of several salan-type Cu II complexes. Suitable crystals suitable for X-ray diffraction were obtained for several of the CuII complexes, including a half-salen compound, revealing square-planar coordination environments common to d9 species. The CuII-salan complexes are tested as catalysts in sulfoxidation, alkene oxidation, and oxidative naphthol coupling. At room temperature the compounds exhibit low to moderate catalytic activity in sulfoxidations and alkene oxidations, but no activity in oxidative naphthol coupling. The saturated coordination environments around the Cu centers probably are the main reason for the lower catalytic activities compared to the Ti- and V-salan analogs. Spectroscopic and mass spectrometry studies revealed that the CuII-salan complexes decompose, in the presence of H2O2, significantly faster at 40 °C than at room temperature. The catalytic activity observed is probably due to the CuII-salan degradation products, observed in the mass spectrometry studies, and not to the original CuII-salan precursors.
One-pot synthesis of silica gel confined functional ionic liquids: Effective catalysts for deoximation under mild conditions
Li, Dongmei,Shi, Feng,Guo, Shu,Deng, Youquan
, p. 265 - 268 (2004)
Several acid-functional ionic liquids were physically confined into the silica gel through a sol-gel process and used as effective catalysts for deoximation reactions, which proceeded under ambient temperatures without addition of any co-catalysts or oxidizing and reducing agents.
Nanostructured rutile TiO2 for selective photocatalytic oxidation of aromatic alcohols to aldehydes in water
Yurdakal, Sedat,Palmisano, Giovanni,Loddo, Vittorio,Augugliaro, Vincenzo,Palmisano, Leonardo
, p. 1568 - 1569 (2008)
Selective photocatalytic oxidation of aromatic alcohols to aldehydes was performed in water in the presence of TiO2 rutile photocatalysts that exhibited a low degree of crystallinity. The nanostructured rutile samples, prepared ex TiCl4 at very low temperature, ensured a selectivity toward the aldehyde 3 to 4-fold higher than the commercial rutile tested (Sigma-Aldrich). Copyright
Gold nanoparticle-modified TiO2/SBA-15 nanocomposites as active plasmonic photocatalysts for the selective oxidation of aromatic alcohols
Chen, Yu,Li, Weizun,Wang, Jingyu,Yang, Qian,Hou, Qidong,Ju, Meiting
, p. 70352 - 70363 (2016)
The catalytic performance of noble-metal on mesoporous silica hosts has been widely investigated because the effects of surface plasmon resonance can open new avenues for the improvement of catalytic performance under light irradiation. In this study, a s
Lewis acid-catalyzed reactions of ethyl diazoacetate with aldehydes. Synthesis of α-formyl esters by a sequence of aldol reaction and 1,2- nucleophilic rearrangement
Kanemasa, Shuji,Kanai, Toshio,Araki, Takahiro,Wada, Eiji
, p. 5055 - 5058 (1999)
Ethyl diazoacetate reacts with a variety of aldehydes in the presence of a Lewis acid catalyst to give either β-keto esters or α-formyl esters, the types of products mainly depending upon the nature of Lewis acid catalysts employed. Reactions catalyzed by Lewis acids such as SnCl2 and SnCl4 provide β-keto esters via nucleophilic 1,2-hydride migration, while those catalyzed by trimethylsilyl triflate give α-formyl esters via migration of the substituent of the aldehyde. Reaction mechanisms are discussed.
Scholl,Hilgers
, p. 648 (1903)
Facile one-pot synthesis of anisaldehyde
Yu, Jing,Shen, Minmin,Deng, Lianli,Gan, Lu,Ha, Chengyong
, p. 541 - 543 (2012)
At room temperature, anisaldehyde (4-methoxybenzaldehyde) is synthesized based on the ozonolysis of anethole (1-methoxy-4-(1-propenyl)-benzene) in a novel and environmentally friendly system composed of water and ethyl acetate. In the presence of water, ozonolysis of anethole results in the direct formation of anisaldehyde, avoiding the isolation or decomposition of ozonide.
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Mandell et al.
, p. 1461 (1977)
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Rakoutz et al.
, p. 3723 (1978)
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Aminolysis of 6-[1-(2,6-difluorophenyl)cyclopropyl]-5-methyl-2-(nitroamino)pyrimidin-4(3H)-one
Novakov,Brunilina,Vernigora,Kirillov,Mkrtchyan,Navrotskii,Sheikin,Yablokov,Ruchko,Kachala
, p. 1844 - 1850 (2017)
The aminolysis of 6-[1-(2,6-difluorophenyl)cyclopropyl]-5-methyl-2-(nitroamino)pyrimidin-4(3H)-one with various amines in butan-1-ol and under solvent-free conditions is successful when the amino group in the reagent is sterically unshielded and the reaction medium is characterized by a high dielectric permittivity. Reactions of the title compound with sterically shielded amines are accompanied by alcoholysis where the amine acts as a base catalyst.
Demonstration of the chemical competence of an iminodiazonium ion to serve as the reactive intermediate of a schmidt reaction
Richard, John P.,Amyes, Tina L.,Lee, Yong-Gu,Jagannadham, Vandanapu
, p. 10833 - 10834 (1994)
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Copper-Catalyzed Cleavage of Unstrained C-C Bonds for the Synthesis of 1-Acyloxy-2,2,6,6-tetramethylpiperidines from Cyclic or Acyclic Ketones
Jiang, Qijian,Yang, Luo,Zhou, Wang
, p. 2163 - 2168 (2017)
A copper-catalyzed approach for the synthesis of 1-acyloxy-2,2,6,6-tetramethylpiperidines through the C-C bond cleavage of cyclic or acyclic ketones was developed. In this chemistry, a combination of CuCl 2 ·2H 2 O, 1,10-phenanthroline monohydrate, and aniline was crucial for the formation of the desired products by the reaction of ketones with TEMPO. This research provides a new strategy for the further transformation of α-aryl cyclic or acyclic ketones.
Zeolite-supported chromium(VI) oxide: A mild, efficient, and inexpensive reagent for oxidative deprotection of trimethylsilyl ethers under microwave irradiation
Heravi, Majid M.,Hydarzadeh, Fereshteh,Farhangi, Yahya,Ghassemzadeh, Mitra
, p. 1473 - 1475 (2004)
Primary and secondary trimethylsilyl ethers are efficiently converted, to the corresponding carbonyl compounds using HZSM-5 zeolite-supported CrO 3 under microwave irradiation in solventless system.
Synthesis of α-CF3 ketones from alkenes and electrophilic trifluoromethylating reagents by visible-light driven photoredox catalysis
Li, Lun,Chen, Qing-Yun,Guo, Yong
, p. 79 - 83 (2014)
α-Trifluoromethyl ketones are important fluorinated intermediates and products in chemical synthesis and medicinal development. Herein, visible light-catalyzed photoredox trifluoromethylation of 1-aryl-2-alkyl substituted alkenes using an electrophilic tr
The oxidation of sulfides by chromium(V)
Lepage, Carmela R. Jackson,Mihichuk, Lynn,Lee, Donald G.
, p. 75 - 80 (2003)
The mechanism for the oxidation of sulfides by [(me4-salen)CrV(O)(pyO)]CF3SO3, where me4-salen is 8,8,8',8'-tetramethylsalen and pyO is pyridine N-oxide, has been investigated. Results from Hammett correlations on the rates of oxidation of substituted thioanisoles, frontier molecular orbital calculations, and product studies are consistent with a mechanism that is initiated by a single electron transfer to give a radical cation intermediate.
Detailed Mechanistic Study of the Non-enzymatic Formation of the Discoipyrrole Family of Natural Products
Colosimo, Dominic A.,Macmillan, John B.
, p. 2383 - 2388 (2016)
Discoipyrroles A-D (DPA-DPD) are recently discovered natural products produced by the marine bacterium Bacillus hunanensis that exhibit anticancer properties in vitro. Initial biosynthetic studies demonstrated that DPA is formed in the liquid fermentation medium of B. hunanensis from three secreted metabolites through an unknown but protein-independent mechanism. The increased identification of natural products that depend on non-enzymatic steps creates a significant need to understand how these different reactions can occur. In this work, we utilized 15N-labeled starting materials and continuous high-sensitivity 1H-15N HMBC NMR spectroscopy to resolve scarce reaction intermediates of the non-enzymatic discoipyrrole reaction as they formed in real time. This information guided supplemental experiments using 13C- and 18O-labeled materials to elucidate the details of DPA's non-enzymatic biosynthesis, which features a highly concerted pyrrole formation and necessary O2-mediated oxidation. We have illustrated a novel way of using isotopically enhanced two-dimensional NMR spectroscopy to interrogate reaction mechanisms as they occur. In addition, these findings add to our growing knowledge of how multicomponent non-enzymatic reactions can occur through inherently reactive bacterial metabolites.
Highly selective electrocatalytic dehydrogenation at low applied potential catalyzed by an Ir organometallic complex
Bonitatibus, Peter J.,Rainka, Matthew P.,Peters, Andrea J.,Simone, Davide L.,Doherty, Mark D.
, p. 10581 - 10583 (2013)
A homogeneous organometallic Ir complex was shown to catalyze the electro-oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde at a very low applied potential with remarkably high selectivity and Faradaic efficiency. In the chemical catalysis, when stoi
A hydrophilic covalent organic framework for photocatalytic oxidation of benzylamine in water
Liu, Ziqian,Su, Qing,Ju, Pengyao,Li, Xiaodong,Li, Guanghua,Wu, Qiaolin,Yang, Bing
, p. 766 - 769 (2020)
The highly hydrophilic COF material (TFPT-BMTH) was constructed by pore surface functionalizing strategy, and exhibited excellent porosity, high crystallinity, and good thermal and chemical stability. The resulting COF exhibits significant catalytic activity and recyclability together with environmental benignity in photocatalytic oxidation of benzylamine in water under ambient conditions.
A convenient deprotection of 1,3-dithiane derivatives with ferric nitrate under heterogeneous conditions
Hirano, Masao,Ukawa, Ken,Yakabe, Shigetaka,Morimoto, Takashi
, p. 1527 - 1533 (1997)
1,3-Dithianes derived from aromatic, aliphatic, and alicyclic ketones or aldehydes can be conveniently converted to the parent carbonyl compounds with a combination of ferric nitrate and silica gel in hexane in excellent to quantitative yields.
Nascent-HBr-Catalyzed Removal of Orthogonal Protecting Groups in Aqueous Surfactants
Bera, Smritilekha,Gupta, Shilpi,Mondal, Dhananjoy
, (2020)
Organic reactions in the aqueous environment have recently emerged as a promising research area. The generation of nascent-HBr from the slow hydrolysis of the dispersed catalyst, benzyl bromide, with the interior water present in the hydrophobic core of the confined micellar medium in aqueous surfactant is described for the first time. The sustained-release nascent-HBr enabled the chemoselective cleavages of acid-sensitive orthogonal functionalities present in carbohydrates, amino alcohols, and hydroxylated acyclic compounds in good to excellent yields.
Outstanding response of carbon nitride photocatalysts for selective synthesis of aldehydes under UV-LED irradiation
Lopes, Joana C.,Sampaio, Maria J.,Fernandes, Raquel A.,Lima, Maria J.,Faria, Joaquim L.,Silva, Cláudia G.
, p. 32 - 38 (2020)
The photocatalytic conversion of alcohols into the corresponding aldehydes constitutes an important reaction in organic synthesis. Optical semiconductors based on carbon nitride were prepared by thermal condensation of dicyandiamide followed by a thermal
Transition metal-free and substrate-selective oxidation of alcohols using water as an only solvent in the presence of β-cyclodextrin
Ji, Hong-Bing,Shi, Dong-Po,Shao, Ming,Li, Zhong,Wang, Le-Fu
, p. 2517 - 2520 (2005)
A facile, substrate-selective and transition metal-free oxidation of benzylic and allylic alcohols catalyzed by β-cyclodextrin with NaOCl oxidant using water as an only solvent was developed.
Chemoselective aerobic oxidation of primary alcohols catalyzed by a ruthenium complex
Miyata, Atsushi,Murakami, Masakazu,Irie, Ryo,Katsuki, Tsutomu
, p. 7067 - 7070 (2001)
In the presence of secondary alcohols, primary alcohols are selectively oxidized to aldehydes under aerobic conditions by using a (nitrosyl)Ru(salen) complex as catalyst.
Thermotropic phase transitions in 5,15-bis(4-alkoxyphenyl)octaalkylporphyrins
Sudhoelter, Ernst J. R.,Van Dijk, Marinus,Teunis, Cees J.,Sanders, Georgine M.,Harkema, Sybolt,Van De Velde, Gerrit M. H.,Schouten, Pieter G.,Warman, John M.
, p. 357 - 363 (1996)
Nineteen novel alkyl substituted porphyrins have been synthesized and their thermal phase behaviour has been investigated in detail. Twelve compounds showed a reversible phase transition below the isotropization temperature. From time resolved microwave conductivity (TRMC) measurements and powder X-ray diffractometry it was concluded that the molecular packing does not change significantly at the lower phase transition temperature and that the porphyrin cores occupy isolated positions. Single X-ray diffraction measurements showed that the porphyrins are arranged in a layered structure and that the space between the layers is occupied by the alkyl substituents of the pyrrole units. The phase transitions at the lower temperature were therefore identified as changes in the crystal ordering of the porphyrins.
Optimization of a biocatalytic single-step alkene cleavage of aryl alkenes
Mang, Harald,Gross, Johannes,Lara, Miguel,Goessler, Christian,Schoemaker, Hans E.,Guebitz, Georg M.,Kroutil, Wolfgang
, p. 3350 - 3354 (2007)
The oxidative cleavage of a C{double bond, long}C double bond adjacent to an aryl moiety was achieved in the presence of a protein preparation of Trametes hirsuta G FCC 047 to yield the corresponding aldehydes. Molecular oxygen was the only oxidant required. All positive substrates had a C{double bond, long}C bond conjugated to an aromatic system, all other compounds tested not fulfilling this requirement were non-substrates. The optimum reaction conditions are 20 °C, pH 6-6.5, 15% v/v ethanol as co-solvent at an apparent oxygen pressure of 2 bar.
Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
, (2021/11/30)
Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
Urchin-like Nb2O5 hollow microspheres enabling efficient and selective photocatalytic C–C bond cleavage in lignin models under ambient conditions
Chen, Huan,Hong, Donghui,Long, Donghui,Niu, Bo,Wan, Kun,Wang, Junjie,Zhang, Yayun
supporting information, (2022/03/27)
Selective cleavage of robust C?C bonds to harvest value-added aromatic oxygenates is an intriguing but challenging task in lignin depolymerization. Photocatalysis is a promising technology with the advantages of mild reaction conditions and strong sustainability. Herein, we show a novel urchin-like Nb2O5 hollow microsphere (U-Nb2O5 HM), prepared by one-pot hydrothermal method, are highly active and selective for Cα?Cβ bond cleavage of lignin β-O-4 model compounds under mild conditions, achieving 94% substrate conversion and 96% C?C bond cleavage selectivity. Systematic experimental studies and density functional theory (DFT) calculations revealed that the superior performance of U-Nb2O5 HMs arises from more exposed active sites, more efficient free charge separation and the active (001) facet, which facilitates the activation of Cβ?H bond of lignin models and generate key Cβ radical intermediates by photogenerated holes, further inducing the Cα?Cβ bond cleavage to produce aromatic oxygenates. This work could provide some suggestions for the fabrication of hierarchical photocatalysts in the lignin depolymerization system.
One-Pot Biocatalytic In Vivo Methylation-Hydroamination of Bioderived Lignin Monomers to Generate a Key Precursor to L-DOPA
Birmingham, William R.,Galman, James L.,Parmeggiani, Fabio,Seibt, Lisa,Turner, Nicholas J.
, (2022/01/13)
Electron-rich phenolic substrates can be derived from the depolymerisation of lignin feedstocks. Direct biotransformations of the hydroxycinnamic acid monomers obtained can be exploited to produce high-value chemicals, such as α-amino acids, however the reaction is often hampered by the chemical autooxidation in alkaline or harsh reaction media. Regioselective O-methyltransferases (OMTs) are ubiquitous enzymes in natural secondary metabolic pathways utilising an expensive co-substrate S-adenosyl-l-methionine (SAM) as the methylating reagent altering the physicochemical properties of the hydroxycinnamic acids. In this study, we engineered an OMT to accept a variety of electron-rich phenolic substrates, modified a commercial E. coli strain BL21 (DE3) to regenerate SAM in vivo, and combined it with an engineered ammonia lyase to partake in a one-pot, two whole cell enzyme cascade to produce the l-DOPA precursor l-veratrylglycine from lignin-derived ferulic acid.
