- N-Doped carbon encapsulated molybdenum carbide as an efficient catalyst for oxidant-free dehydrogenation of alcohols
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We report molybdenum carbide (Mo2C) encapsulated in N-doped carbon as an efficient and stable catalyst for oxidant-free dehydrogenation of alcohols, prepared by anion exchange of H3PMo12O40 (PMo) with an ionic copolymer (DIM-AN) of dicationic imidazole ionic liquid and acrylonitrile, followed by a two-step carbonization at 400 °C in air and 800 °C in Ar. The synthesized catalyst (PMo@DIM-AN400/800) exhibits outstanding catalytic activity and selectivity for dehydrogenation of various alcohols under oxidant-free conditions and can be steadily reused at least five times for dehydrogenation of benzyl alcohol without changing its crystalline structure. The characterizations and comparative experimental results demonstrate that the active sites for dehydrogenation stem from the Mo2C, as well as the abundant N atoms in the carbon shell, which contribute to the enhancement of catalytic performance. The strategy for the preparation of such N-doped carbon encapsulated Mo2C using polyoxometalate-based ionic hybrids as precursors may open up new opportunities for exploring more transition-metal carbides for more catalytic applications.
- Leng, Yan,Li, Jingjing,Zhang, Chenjun,Jiang, Pingping,Li, Yue,Jiang, Yuchen,Du, Shengyu
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- Solid-Phase Synthesis of Biaryls via the Stille Reaction
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The solid-phase synthesis of biphenyls by heterogenous cross-coupling of trialkylphenylstannanes with aryl electrophiles is described.Tributylphenyltin attached by an amide bond to the Rink amide resin undergoes palladium-catalyzed coupling with aryl triflates and aryl iodides to produce after acid cleavage 4-biphenylacetamide in 3-15percent yield. 4-Iodophenylacetic acid attached to the Rink amide resin by an amide bond also undergoes heterogeneous palladium-catalyzed coupling with trialkylphenyltins to give after acid cleavage of the support 4-biphenylacetamide in 21-33percent yield. 4-Iodobenzylbromide was then attached to the photocleavable (+/-)-2-methoxy-5--1-oxopropyl>phenylacetamide (NpSSMpact) resin through the formation of a thioether bond.Both substituted and unsubstituted trimethylphenyltins were shown to undergo palladium-catalyzed Stille coupling with the resin bound aryl iodide to give after photolytic cleavage biphenyls containing no residual amide, carboxylic acid, or alcohol appendages.
- Forman, Frank W.,Sucholeiki, Irving
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- Copper(II) Complexes of 2,2:6,2-Terpyridine Derivatives for Catalytic Aerobic Alcohol Oxidations - Observation of Mixed-Valence CuICuII Assembles
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The reactions of copper(II) salts with simple terpyridine (tpy) ligands gave mononuclear monoligand complexes 1-3, of which two new structures have been characterized by X-ray crystallography. These complexes were applied as catalysts for the oxidation of benzylic alcohol to benzaldehyde in air in the presence of the radical 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO). Copper complexes 1 and 2 are efficient catalysts for the reactions in water at 70 C with 4-dimethylaminopyridine (DMAP) as an extra base. The influence of TEMPO on the formation of new reactive intermediates during the catalytic reactions was tentatively investigated by introducing TEMPO into the reaction solutions of tpy derivatives with copper dichloride. Two new complexes with interesting solid-state structures resulting from these reactions have been isolated and characterized. The coordination reactions in the presence of TEMPO led to new mixed-valence CuICuII supramolecular assembles (4 and 5), although they adopt either discrete complex or 1D polymeric structures. Further catalytic studies indicated that the mixed-valence assembles 4 and 5 displayed higher catalytic activity than those of the mononuclear complexes under milder conditions. The relationship between the molecular structures of diverse copper complexes and their reactivity is discussed on the basis of the results obtained.
- Zhang, Guoqi,Liu,Yang, Chengxiong,Li, Li,Golen, James A.,Rheingold, Arnold L.
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- Influence of catalyst nuclearity on copper-catalyzed aerobic alcohol oxidation
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Reactions of CuX with the bis(triazolyl) ligand Hbtm [bis(1-benzyl-1H-1,2,3-triazol-4-yl)phenylmethanol] in CH2Cl2 afforded trinuclear copper(ii) complexes with a core structure (μ-X)Cu3(μ-κ3-N,O,N-btm)3(L)2+ [X = Cl, L = CH3OH (1); X = Br, L = H2O (2)], while a similar reaction of [Cu(CH3CN)4](PF6) with the mono(triazolyl) ligand HPhtm [(1-benzyl-1H-1,2,3-triazol-4-yl)diphenylmethanol] resulted in the mononuclear complex [Cu(κ2-N,O-Phtm)(κ2-N,O-HPhtm)(κ1-N-HPhtm)][PF6] (3). The structural characterization of these complexes was made by single-crystal X-ray crystallography in combination with elemental and ESI mass analyses. Catalytic studies toward aerobic oxidation of benzyl alcohol to benzaldehyde revealed that the trinuclear 1 and 2 exhibited higher activities than the mononuclear 3 in both CH3CN and EtOH/H2O solvent systems.
- Krittametaporn, Nuttaporn,Chantarojsiri, Teera,Virachotikul, Arnut,Phomphrai, Khamphee,Kuwamura, Naoto,Kojima, Tatsuhiro,Konno, Takumi,Sangtrirutnugul, Preeyanuch
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- Practical and efficient ipso-iodination of arylboronic acids via KF/I2 system
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A facile and effective iododeboronation of variously substituted aryl and heteroarylboronic acids through activation and subsequent ipso-introduction of iodine is presented. The use of KF and I2 at 80 °C in 1,4-dioxane furnishes iodinated compounds in high yields.
- Tramutola, Francesco,Chiummiento, Lucia,Funicello, Maria,Lupattelli, Paolo
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- Synthesis and aggregation properties of boron-dipyrromethene dyes conjugated with guanine units
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Two boron-dipyrromethene dyes bearing a conjugated guanine unit (G-BODIPYs) 1 and 2 were synthesized and fully characterized. The self-assembly properties of these dyes were investigated by X-ray crystallography, 1H NMR and UV-vis spectroscopy. As revealed by X-ray crystal structure studies, G-BODIPY 1 self-assembled into ribbon-like structures due to the intermolecular hydrogen bonding and π-π stacking interaction. Concentration-dependent 1H NMR experiments confirmed the formation of hydrogen bonds of the guanine units in solution for both dye 1 and 2. In the presence of K+, the characteristic signals for the formation of cyclic G-quadruplex structures were observed in the 1H NMR study. Aggregation of G-BODIPY dyes was further monitored by UV-vis absorption spectroscopy by varying the solvent polarity and temperature. H-type aggregates of dye 1, which was characterized by a new hypsochromically shifted absorption band with λmax = 461 nm, was obtained. In the presence of K+, the enhancement of stability was observed for the H-aggregates of dye 1.
- Li, Fen,Zhang, Yongjie,Zhou, Lina,Zhang, Xin,Chen, Zhijian
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- Ti3C2/TiO2 nanowires with excellent photocatalytic performance for selective oxidation of aromatic alcohols to aldehydes
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The Ti3C2/TiO2 nanowires photocatalyst is synthesized by in situ growth through a facile hydrothermal method and mild chemical processes for the first time. The Ti3C2/TiO2-0.7 exhibits high photocatalytic activity for selective oxidation of aromatic alcohols to aldehydes under visible light irradiation. The 92% benzyl alcohol conversion and almost 99% selectivity is observed for the Ti3C2/TiO2-0.7 photocatalyst, higher than that of P25 and TiO2 nanowires. Results reveal that the photocatalytic activity of this photocatalyst is mainly attributed to the introduction of Ti3C2, which results in the narrowed energy band gap by altering the position of CB and VB of TiO2 and the enhanced light-harvesting ability. In our design, a Schottky barrier is established between Ti3C2 and TiO2 nanowires to improve the separation efficiency of photogenerated electrons and holes. Significantly, the feasible reaction mechanism of Ti3C2/TiO2 nanowires photocatalyst under visible light is proposed.
- Xu, Chong,Yang, Fan,Deng, Bijian,Zhuang, Yue,Li, Dingyao,Liu, Baocheng,Yang, Wang,Li, Yongfeng
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- Kinetics and oxidation of substituted benzyl alcohols by phenyliodoso acetate
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Oxidation of benzyl alcohol and some meta- and para- substituted alcohols by phenyliodoso acetate (PIA) in t-butyl alcohol-water medium (50:50) leads to the formation of corresponding benzaldehyde. The stoichiometry of the reaction was found to be 1:1. The reaction was first order each in substrate and oxidant concentrations. This reaction was studied at four different temperatures and the activation parameters were calculated. Correlation analysis was carried out using Taft's and Swain's dual substituent parameter (DSP) equation. The rate data of meta- compounds showed good correlation with (F,R) values, para-substituted benzyl alcohols showed good correlation with σIσR + A suitable mechanism has been proposed.
- Girija,Aruna
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- Synthesis of a single-molecule nanotruck
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We report the synthesis of a new nanovehicle, a porphyrin-based nanotruck. The porphyrin inner core was designed for possible transportation of metals and small molecules across a surface.
- Sasaki, Takashi,Morin, Jean-Fran?ois,Lu, Meng,Tour, James M.
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- Hypervalent Activation as a Key Step for Dehydrogenative ortho C-C Coupling of Iodoarenes
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Building on earlier results, a direct metal-free α- arylation of substituted cyclic 1,3-diones using ArI(O2CCF3)2 reagents has been developed; unlike other arylative approaches, the arylated products retain the iodine substituent ortho to the newly formed C-C bond. The mechanism is explored by using DFT calculations, which show a vanishingly small activation barrier for the C-C bond-forming step. In fact, taking advantage of an efficient in situ hypervalent activation, the iodoarenes are shown to undergo a cross- dehydrogenative C-C coupling at the C-H ortho to the iodine. When Oxone is used as terminal oxidant, the process is found to benefit from a rapid initial formation of the hypervalent ArI(OR)2 species and the sulfate-accelerated final coupling with a ketone. This method complements the ipso selectivity obtained in the metal-catalyzed α-arylation of carbonyl compounds.
- Wu, Yichen,Arenas, Ismael,Broomfield, Lewis Marc,Martin, Eddy,Shafir, Alexandr
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- Acetylenic Scaffolding with Subphthalocyanines
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A new boron subphthalocyanine (SubPc) derivative with a terminal alkyne substituent on the central boron atom was prepared by substitution of a triflate at the boron atom with but-3-yn-1-ol. This compound was shown to be a versatile building block for metal-catalyzed coupling reactions, such as modified Glaser-Hay, Cadiot-Chodkiewicz, and Sonogashira reactions as well as the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). For example, metal-catalyzed reactions provided access to a SubPc dimer containing a butadiyne bridging unit, two different SubPc-fullerene dyads as well as two cross-conjugated SubPc-tetraethynylethene (TEE) scaffolds. These TEEs containing two silyl-protected alkyne units are potential building blocks for further acetylenic scaffolding. The work shows how the axial position is post-functionalized in steps not involving a substitution reaction at the central boron atom, which is otherwise often used as the terminal step in axial functionalization of SubPcs.
- Gotfredsen, Henrik,Jevric, Martyn,Kadziola, Anders,Nielsen, Mogens Brondsted
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- A 4-MeO-TEMPO, PEG-NO2 and HCl catalytic system for highly efficient aerobic oxidation of alcohols
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A combination of 4-MeO-TEMPO/PEG-NO2/HCl for catalytic aerobic oxidation of alcohol is described. A wide range of alcohols was efficiently oxidized to the corresponding carbonyl compounds by using this oxidation system and the turnover number (TON) for benzyl alcohol oxidation reached up to 56000. Georg Thieme Verlag Stuttgart - New York.
- Tao, Jianwei,Lu, Qiongqiong,Chu, Changhu,Liu, Renhua,Liang, Xinmiao
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- Chiral tetranuclear and dinuclear copper(ii) complexes for TEMPO-mediated aerobic oxidation of alcohols: Are four metal centres better than two?
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The one-pot reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde, (R)-2-aminoglycinol and Cu(OAc)2·2H2O in a 1:1:1 ratio in the presence of triethylamine led to the isolation of X-ray quality crystals of the chiral complex (R)-1 in high yield. The single crystal structure of (R)-1 reveals a tetranuclear copper(ii) complex that contains a {Cu 4(μ-O)2(μ3-O)2N 4O4} core. A reaction using (1S,2R)-2-amino-1,2- diphenylethanol as precursor under the same conditions generated the chiral complex (S,R)-2; its structure was determined by single crystal X-ray crystallography and was found to contain a {Cu2(μ-O) 2N2O2} core. Both (R)-1 and (S,R)-2 have been used for catalytic aerobic oxidation of benzylic alcohols in combination with the TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) radical. (R)-1 selectively catalyses the conversion of various aromatic primary alcohols to the corresponding aldehydes with high yields (99%) and TONs (770) in the air, while (S,R)-2 exhibits less promising catalytic performance under the same reaction conditions. The role of the cluster structures in (R)-1 and (S,R)-2 in controlling the reactivity towards aerobic oxidation reactions is discussed.
- Zhang, Guoqi,Proni, Gloria,Zhao, Sherry,Constable, Edwin C.,Housecroft, Catherine E.,Neuburger, Markus,Zampese, Jennifer A.
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- Bi- and trinuclear σ-aryl complexes of iron and manganese
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The binuclear and trinuclear aryl σ-complexes of iron and manganese have been prepared by the palladium-catalysed reactions of m-diiodobenzene, p-diiodobenzene or 1,3,5-triiodobenzene with cyclopentadienyldicarbonyliron and manganese pentacarbonyl anions.
- Artamkina, Galina A.,Beletskaya, Irina P.
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- Facile aromatic finkelstein iodination (AFI) reaction in 1,3-dimethyl-2-imidazolidinone (DMI)
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In this communication, we report the superior role of 1,3-dimethyl-2- imidazolidinone (DMI) as a solvent for aromatic Finkelstein iodination (AFI), the conversion of aryl bromides to aryl iodides. DMI accelerates the reaction rate and affords product(s) that could not be prepared using previous methods. Our findings for AFI avoid the use of toxic solvents such as N,N-dimethylformamide and hexamethylphosphoramide. Taylor & Francis Group, LLC.
- Yamashita, Ken-Ichi,Tsuboi, Michihiro,Asano, Motoko S.,Sugiura, Ken-Ichi
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- Cu-Mn Bimetallic Complex Immobilized on Magnetic NPs as an Efficient Catalyst for Domino One-Pot Preparation of Benzimidazole and Biginelli Reactions from Alcohols
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An efficient magnetically recyclable bimetallic catalyst by anchoring copper and manganese complexes on the Fe3O4 NPs was prepared and named as Fe3O4@Cu-Mn. It was founded as a powerful catalyst for the domino one-pot oxidative benzimidazole and Biginelli reactions from benzyl alcohols as a green protocol in the presence of air, under solvent-free and mild conditions. Fe3O4@Cu-Mn NPs were well characterized by FT-IR, XRD, FE-SEM, TEM, VSM, TGA, EDX, DLS, and ICP analyses. The optimum range of parameters such as time, temperature, amount of catalyst, and solvent were investigated for the domino one-pot benzimidazole and Biginelli reactions to find the optimum reaction conditions. The catalyst was compatible with a variety of benzyl alcohols, which provides favorable products with good to high yields for all of derivatives. Hot filtration and Hg poisoning tests from the nanocatalyst revealed the stability, low metal leaching and heterogeneous nature of the catalyst. To prove the synergistic and cooperative effect of the catalytic system, the various homologues of the catalyst were prepared and then applied to a model reaction separately. Finally, the catalyst could be filtered from the reaction mixture simply, and reused for five consecutive cycles with a minimum loss in catalytic activity and performance. Graphic Abstract: A new magnetically recyclable Cu/Mn bimetallic catalyst has been developed for domino one-pot oxidation-condensation of benzimidazole and Biginelli reactions from alcohols. [Figure not available: see fulltext.]
- Nasseri, Mohammad Ali,Rezazadeh, Zinat,Kazemnejadi, Milad,Allahresani, Ali
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p. 1049 - 1067
(2020/09/11)
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- Zwitterion-induced organic-metal hybrid catalysis in aerobic oxidation
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In many metal catalyses, the traditional strategy of removing chloride ions is to add silver salts via anion exchange to obtain highly active catalysts. Herein, we reported an alternative strategy of removing chloride anions from ruthenium trichloride using an organic [P+-N-] zwitterionic compound via multiple hydrogen bond interactions. The resultant organic-metal hybrid catalytic system has successfully been applied to the aerobic oxidation of alcohols, tetrahydroquinolines, and indolines under mild conditions. The performance of zwitterion is far superior to that of many other common Lewis bases or Br?nsted bases. Mechanistic studies revealed that the zwitterion triggers the dissociation of chloride from ruthenium trichloride via nonclassical hydrogen bond interaction. Preliminary studies show that the zwitterion is applicable to catalytic transfer semi-hydrogenation.
- Hu, Rong-Bin,Lam, Ying-Pong,Ng, Wing-Hin,Wong, Chun-Yuen,Yeung, Ying-Yeung
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p. 3498 - 3506
(2021/04/07)
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- Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones
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We have developed a cerium-photocatalyzed aerobic oxidation of primary and secondary benzylic alcohols to aldehydes and ketones using inexpensive CeCl3 7H2O as photocatalyst and air oxygen as the terminal oxidant.
- K?nig, Burkhard,Kumar, Sumit,Stahl, Jessica,Yatham, Veera Reddy,Yedase, Girish Suresh
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supporting information
p. 1727 - 1732
(2021/08/05)
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- Metal- And additive-free C-H oxygenation of alkylarenes by visible-light photoredox catalysis
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A metal- and additive-free methodology for the highly selective, photocatalyzed C-H oxygenation of alkylarenes under air to the corresponding carbonyls is presented. The process is catalyzed by an imide-acridinium that forms an extremely strong photooxidant upon visible light irradiation, which is able to activate inert alkylarenes such as toluene. Hence, this is an easy to perform, sustainable and environmentally friendly oxidation that provides valuable carbonyls from abundant, readily available compounds.
- García Manche?o, Olga,Kuhlmann, Jan H.,Pérez-Aguilar, María Carmen,Piekarski, Dariusz G.,Uygur, Mustafa
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supporting information
p. 3392 - 3399
(2021/05/21)
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- Mild oxidation of benzyl alcohols to benzyl aldehydes or ketones catalyzed by visible light
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Induced by visible light, mild oxidation condition to prepare benzyl aldehydes or ketones have been developed by using bromotrichloromethane as photochemical oxidant. This method avoids high temperature, pressure and peroxidation with only visible light as the green driving force.
- Cheng, Dongping,Li, Xiaonian,Ren, Shujian,Xu, Xiaoliang
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supporting information
(2021/07/02)
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- Photo-tunable oxidation of toluene and its derivatives catalyzed by TBATB
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In this report, tetrabutylammonium tribromide (TBATB) was introduced as an efficient visible light active catalyst to carry out the aerobic oxidation of toluene, its derivatives, and some of methyl arenes to benzaldehydes, benzoic acids and ketones in good to high yields. All the oxidation reactions were performed under mild conditions using oxygen as a green oxidant, a catalytic amount of TBATB under blue (460 nm), royal blue (430 nm), and violet LED (400 nm) irradiation. It was found that the reactions selectivity was significantly affected by changing the solvent (from CH3CN to EtOAc) and LED wavelength (from blue to violet). In the following, our mechanistic studies revealed that the visible light oxidation of toluenes and methyl arenes over TBATB could be following a benzyl peroxy radical intermediate.
- Mardani, Atefeh,Kazemi, Foad,Kaboudin, Babak
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method includes the steps of: (A) providing a compound (I) with an unsaturated double bond, a trifluoromethyl-containing reagent, and a catalyst; wherein, the catalyst is represented by Formula (II): M(O)mL1yL2z??(II);wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and(B) mixing the compound with an unsaturated double bond and the trifluoromethyl-containing reagent to perform an oxidative cleavage of the compound with the unsaturated double bond by using the catalyst in air or under oxygen atmosphere condition to obtain a compound represented by Formula (III):
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Paragraph 0071; 0077
(2021/07/10)
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- METHOD FOR OXIDATIVE CLEAVAGE OF COMPOUNDS WITH UNSATURATED DOUBLE BOND
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A method for oxidative cleavage of a compound with an unsaturated double bond is provided. The method comprises the following step: (A) providing a compound (I) with an unsaturated double bond, a reagent with trifluoromethyl, and a catalyst; wherein the catalyst is represented by the following formula (II): M(O)mL1yL2z (II); wherein, M, L1, L2, m, y, z, R1, R2 and R3 are defined in the specification; and (B) mixing the compound with an unsaturated double bond and the reagent with a trifluoromethyl to perform an oxidation of the compound with the unsaturated double bond by using the catalyst at air or an oxygen condition to get a compound presented as formula (III):
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Paragraph 0053-0054; 0062-0063
(2021/03/19)
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- Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation
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Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C?H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.
- Wang, Man,Liang, Gan,Wang, Yunhao,Fan, Tao,Yuan, Baoling,Liu, Mingxian,Yin, Ying,Li, Liangchun
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supporting information
p. 9674 - 9685
(2021/06/09)
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- Copper-catalyzed method for preparing aldehyde or ketone compound by oxidizing alcohol with oxygen as oxidizing agent and application
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The invention discloses a copper-catalyzed method for preparing an aldehyde or ketone compound by oxidizing alcohol with oxygen as an oxidizing agent. Reaction is performed in an organic solvent for 4-48 hours at room temperature by using copper salt and nitroxide free radicals as catalysts and oxygen or air as an oxidizing agent to efficiently oxidize an alcohol compound into the corresponding aldehyde or ketone compound. The method is simple to operate, free of chlorides corrosive to equipment, available in raw materials and reagents, mild in reaction conditions, wide in substrate universality, good in functional group compatibility, convenient in separation and purification, environmentally friendly in the whole process and free of pollution, and is a method suitable for industrial production.
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Paragraph 0028-0030; 0151-0153; 0184-0186
(2020/08/18)
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- Organophotoredox-Mediated Amide Synthesis by Coupling Alcohol and Amine through Aerobic Oxidation of Alcohol
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The combination of an organic photocatalyst [4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6 dicyanobenzene) or 5MeOCzBN (2,3,4,5,6-pentakis(3,6-dimethoxy-9 H-carbazol-9-yl)benzonitrile)], quinuclidine, and tetra-n-butylammonium phosphate (hydrogen-bonding catalyst) was employed for amide bond formations. The hydrogen-bonded OH group activated the adjacent C?H bond of alcohols towards hydrogen atom transfer (HAT) by a radical species. The quinuclidinium radical cation, generated through single-electron oxidation of quinuclidine by the photocatalyst, employed to abstract a hydrogen atom from the α-C?H bond of alcohols selectively due to a polarity effect-produced α-hydroxyalkyl radical, which subsequently converted to the corresponding aldehyde under aerobic conditions. Then the coupling of the aldehyde and an amine formed a hemiaminal intermediate that upon photocatalytic oxidation produced the amide.
- Samanta, Samya,Shah, Sk. Sheriff,Shee, Maniklal,Singh, Amit Kumar,Singh, N. D. Pradeep,Venkatesh, Yarra
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supporting information
(2020/03/05)
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- Sequential Connection of Mutually Exclusive Catalytic Reactions by a Method Controlling the Presence of an MOF Catalyst: One-Pot Oxidation of Alcohols to Carboxylic Acids
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A functionalized metal-organic framework (MOF) catalyst applied to the sequential one-pot oxidation of alcohols to carboxylic acids controls the presence of a heterogeneous catalyst. The conversion of alcohols to aldehydes was acquired through aerobic oxidation using a well-known amino-oxy radical-functionalized MOF. In the same flask, a simple filtration of the radical MOF with mild heating of the solution completely altered the reaction media, providing radical scavenger-free conditions suitable for the autoxidation of the aldehydes formed in the first step to carboxylic acids. The mutually exclusive radical-catalyzed aerobic oxidation (the first step with MOF) and radical-inhibited autoxidation (the second step without MOF) are sequentially achieved in a one-pot manner. Overall, we demonstrate a powerful and efficient method for the sequential oxidation of alcohols to carboxylic acids by employing a readily functionalizable heterogeneous MOF. In addition, our MOF in-and-out method can be utilized in an environmentally friendly way for the oxidation of alcohols to carboxylic acids of industrial and economic value with broad functional group tolerance, including 2,5-furandicarboxylic acid and 1,4-benzenedicarboxylic acid, with good yield and reusability. Furthermore, MOF-TEMPO, as an antioxidative stabilizer, prevents the undesired oxidation of aldehydes, and the perfect "recoverability"of such a reactive MOF requires a re-evaluation of the advantages of MOFs from heterogeneity in catalytic and related applications.
- Kim, Seongwoo,Lee, Ha-Eun,Suh, Jong-Min,Lim, Mi Hee,Kim, Min
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supporting information
p. 17573 - 17582
(2020/12/22)
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- Nitrile Synthesis by Aerobic Oxidation of Primary Amines and in situ Generated Imines from Aldehydes and Ammonium Salt with Grubbs Catalyst
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Herein, a Grubbs-catalyzed route for the synthesis of nitriles via the aerobic oxidation of primary amines is reported. This reaction accommodates a variety of substrates, including simple primary amines, sterically hindered β,β-disubstituted amines, allylamine, benzylamines, and α-amino esters. Reaction compatibility with various functionalities is also noted, particularly with alkenes, alkynes, halogens, esters, silyl ethers, and free hydroxyl groups. The nitriles were also synthesized via the oxidation of imines generated from aldehydes and NH4OAc in situ. (Figure presented.).
- Utsumi, Tatsuki,Noda, Kenta,Kawauchi, Daichi,Ueda, Hirofumi,Tokuyama, Hidetoshi
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p. 3583 - 3588
(2020/08/05)
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- A Remote ‘Imidazole’-Based Ruthenium(II) Para-Cymene Pre-catalyst for the Selective Oxidation Reaction of Alkyl Arenes and Alcohols
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Herein we disclosed the use of a remote ‘imidazole’-based precatalyst [(para-cymene)RuII(L)Cl]+, C-1 where L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline) for the selective oxidation of a variety of alkyl arenes/heteroarenes and alcohols to their corresponding aldehydes or ketones in presence of tert-butyl hydroperoxide (TBHP). The remote ‘imidazole’ moiety present in the complex facilitates the activation of oxidant and subsequent generation of active species via the release of para-cymene from C-1, which in-turn was less effective without the ‘imidazole’ moiety. The mechanistic features of C-1 promoted oxidation of alkyl arenes were also assessed from spectroscopic, kinetic, and few control experiments. The substrate scope for C-1 promoted oxidation reaction was assessed based on the selective oxidation of 27-different alkyl arenes/heteroarenes and 25 different alcohols to their corresponding aldehydes/ketones in moderate to good yields.
- Dutta, Manali,Bania, Kusum K.,Pratihar, Sanjay
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p. 926 - 932
(2020/03/05)
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- Continuous flow synthesis of aryl aldehydes by Pd-catalyzed formylation of phenol-derived aryl fluorosulfonates using syngas
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This communication describes the palladium-catalyzed reductive carbonylation of aryl fluorosulfonates (ArOSO2F) using syngas as an inexpensive and sustainable source of carbon monoxide and hydrogen. The conversion of phenols to aryl fluorosulfonates can be conveniently achieved by employing the inexpensive commodity chemical sulfuryl fluoride (SO2F2) and base. The developed continuous flow formylation protocol requires relatively low loadings for palladium acetate (1.25 mol%) and ligand (2.5 mol%). Good to excellent yields of aryl aldehydes were obtained within 45 min for substrates containing electron withdrawing substituents, and 2 h for substrates containing electron donating substituents. The optimal reaction conditions were identified as 120 °C temperature and 20 bar pressure in dimethyl sulfoxide (DMSO) as solvent. DMSO was crucial in suppressing Pd black formation and enhancing reaction rate and selectivity. This journal is
- Hanselmann, Paul,Hone, Christopher A.,Hu, Guixian,K?ckinger, Manuel,Kappe, C. Oliver
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p. 22449 - 22453
(2020/07/03)
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- Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
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We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
- Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
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supporting information
(2020/03/25)
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- Nonclassical Phenyl Bioisosteres as Effective Replacements in a Series of Novel Open-Source Antimalarials
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The replacement of one chemical motif with another that is broadly similar is a common method in medicinal chemistry to modulate the physical and biological properties of a molecule (i.e., bioisosterism). In recent years, bioisosteres such as cubane and bicyclo[1.1.1]pentane (BCP) have been used as highly effective phenyl mimics. Herein, we show the successful incorporation of a range of phenyl bioisosteres during the open-source optimization of an antimalarial series. Cubane (19) and closo-carborane (23) analogues exhibited improved in vitro potency against Plasmodium falciparum compared to the parent phenyl compound; however, these changes resulted in a reduction in metabolic stability; unusually, enzyme-mediated oxidation was found to take place on the cubane core. A BCP analogue (22) was found to be equipotent to its parent phenyl compound and showed significantly improved metabolic properties. While these results demonstrate the utility of these atypical bioisosteres when used in a medicinal chemistry program, the search to find a suitable bioisostere may well require the preparation of many candidates, in our case, 32 compounds.
- Tse, Edwin G.,Houston, Sevan D.,Williams, Craig M.,Savage, G. Paul,Rendina, Louis M.,Hallyburton, Irene,Anderson, Mark,Sharma, Raman,Walker, Gregory S.,Obach, R. Scott,Todd, Matthew H.
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p. 11585 - 11601
(2020/12/04)
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- Method for synthesizing aromatic aldehyde through iron catalyzed oxidation allyl aromatic compound
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The invention discloses a method for synthesizing aromatic aldehyde through an iron catalyzed oxidation allyl aromatic compound. According to the specific method, under the promotion effect of hydrogen silane, with air or oxygen as the oxidant, the aromatic aldehyde compound is synthesized through the iron catalyzed oxidation allyl aromatic compound, the reaction temperature is 20-150 DEG C, and the time is 0.25-60 h. The method has the advantages that a catalyst source is wide, the price is low and the environment is protected; an oxidant source is wide, the price is low and no waste is generated; the reaction conditions are mild, selectivity is high and the yield is high; a substrate source is wide and stable; a substrate functional group is high in compatibility and a substrate is widein application range; complicated small molecules are compatible and can be well converted into aldehyde. The target product separation yield can reach up to 96% under the optimized reaction conditions.
- -
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Paragraph 0114-0116; 0151
(2019/06/27)
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- Iron-Catalyzed Aerobic Oxidation of Alcohols: Lower Cost and Improved Selectivity
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An aerobic oxidation reaction of alcohols toward aldehydes or ketones using catalytic amounts of Fe(NO3)3·9H2O, 4-OH-TEMPO, and NaCl has been developed. Compared with the former catalytic system with TEMPO developed in this group, the new protocol using 4-OH-TEMPO, which is much cheaper on an industrial scale, accomplished the transformation with a higher selectivity, especially for aliphatic alcohols toward aldehydes. α,β-Unsaturated alkynals or alkynones can be efficiently synthesized from propargyl alcohols, which has been much less studied in the literature.
- Jiang, Xingguo,Liu, Jinxian,Ma, Shengming
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p. 825 - 835
(2019/05/02)
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- Europium-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes/Ketones and Photoluminescence Tracking
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Europium is a lanthanide rare-earth metal and is known as a key element in luminophore development. Since europium has two relatively stable oxidation states, Eu2+ and Eu3+, which is exceptional among the various lanthanide elements, we have developed a europium-catalyzed aerobic oxidation with external oxidants utilizing the redox cycle of Eu2+/Eu3+. The reaction was performed under mild conditions with a wide substrate scope. The photoluminescence spectra clearly demonstrate the oxidation state changes that occur during the presented europium-catalyzed aerobic oxidation. (Figure presented.).
- Kim, Seongwoo,Kim, Youngik,Jin, Hyomin,Park, Myung Hwan,Kim, Youngjo,Lee, Kang Mun,Kim, Min
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supporting information
(2019/02/05)
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- A Simple, Mild and General Oxidation of Alcohols to Aldehydes or Ketones by SO2F2/K2CO3 Using DMSO as Solvent and Oxidant
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A practical, general and mild oxidation of primary and secondary alcohols to carbonyl compounds proceeds in yields of up to 99% using SO2F2 as electrophile in DMSO as both the oxidant and the solvent at ambient temperature. No moisture- and oxygen-free conditions are required. Stoichiometric amount of inexpensive K2CO3, which generates easy to separate by-products, is used as the base. Thus, 5-gram scale runs proceeded in nearly quantitative yields by a simple filtration as the work-up. The use of a polar solvent such as DMSO, which usually promotes competing Pummerer rearrangement, is also noteworthy. This protocol is compatible with a variety of common N-, O-, and S-functional groups on (hetero)arene, alkene and alkyne substrates (68 examples). The protocol was applied (99% yield) to a formal synthesis of the important cholesterol-lowering drug Rosuvastatin. (Figure presented.).
- Zha, Gao-Feng,Fang, Wan-Yin,Leng, Jing,Qin, Hua-Li
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supporting information
p. 2262 - 2267
(2019/04/17)
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- Metal-ligand cooperativity in a ruthenium(II) complex of bis-azoaromatic ligand for catalytic dehydrogenation of alcohols
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Herein a new Ru-phosphine complex (1) with molecular formula [RuL(PPh3)Cl2] is reported where L is a redox active pincer ligand 2,6-bis(phenylazo)pyridine. The isolated complex has been characterized by usual spectroscopic techniques including single crystal X-ray crystallographic analysis. Complex 1 efficiently catalyzes aerobic oxidation of a wide range of primary and secondary benzylic, allylic, heterocyclic, alicyclic alcohols under mild conditions and is found to be superior over several other Ru (0, +2 and +3), Ru-H and Ru-PPh3 catalysts. Mechanistic studies indicate that a transient Ru-H intermediate is formed in the catalytic cycle which gets switched into a Ru-hydrazo intermediate via hydrogen-walking mechanism. The catalyst is regenerated by aerial oxidation producing H2O2 as a by-product.
- Saha, Tanushri,Pramanick, Rajib,Sengupta, Debabrata,Goswami, Sreebrata
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p. 160 - 166
(2018/09/29)
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- A Transition-Metal-Free One-Pot Cascade Process for Transformation of Primary Alcohols (RCH2OH) to Nitriles (RCN) Mediated by SO2F2
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A new transition-metal-free one-pot cascade process for the direct conversion of alcohols to nitriles was developed without introducing an “additional carbon atom”. This protocol allows transformations of readily available, inexpensive, and abundant alcohols to highly valuable nitriles.
- Jiang, Ying,Sun, Bing,Fang, Wan-Yin,Qin, Hua-Li
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supporting information
p. 3190 - 3194
(2019/05/21)
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- Mono-selective β-C-H arylation of: N -methylated amino acids and peptides promoted by the 2-(methylthio)aniline directing group
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2-(Methylthio)aniline (MTA) directed C(sp3)-H functionalisations are efficient and straightforward protocols for the selective β-modification of N-methylated amino acids. The decreased reactivity of MTA in comparison with the 8-aminoquinoline (AQ) directing group allows for selective monoarylations in high yields without the formation of side products. The protocol is also suitable for the introduction of highly functionalised side chains onto the C-terminal alanines of dipeptides. The MTA directing group can easily be removed, providing free carboxylic acids as valuable building blocks.
- Kinsinger, Thorsten,Kazmaier, Uli
-
supporting information
p. 5595 - 5600
(2019/06/13)
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- Controlled Aerobic Oxidation of Primary Benzylic Alcohols to Aldehydes Catalyzed by Polymer-Supported Triazine-Based Dendrimer-Copper Composites
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A controlled aerobic oxidation of primary benzylic alcohols to the corresponding benzaldehydes by using polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported triazine-based polyethyleneamine dendrimer-copper complexes [PS-PEG-TD2-Cu(II)] was developed. In particular, PS-PEG-TD2-Cu(OAc) 2 efficiently catalyzed the aerobic oxidation of benzylic alcohols in the presence of a catalytic amount of TEMPO under atmospheric conditions to give the corresponding aldehydes in up to quantitative yield. The catalyst was readily recovered by simple filtration and reused four times without significant loss of its catalytic activity.
- Pan, Shiguang,Yan, Shuo,Osako, Takao,Uozumi, Yasuhiro
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p. 1152 - 1156
(2018/04/16)
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- Effects of Ancillary Ligands on Redox and Chemical Properties of Ruthenium Coordinated Azoaromatic Pincer
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In this work, the effect of the electronically different ancillary ligands on the overall properties of the RuIIL moiety (L = 2,6-bis(phenylazo)pyridine) in heteroleptic complexes of general formula [RuLQCl]0/+ was investigated. Four different ancillary ligands (Q) with different electronic effects were used to prepare the heteroleptic compounds from the precursor complex, [RuL(CH3CN)Cl2] (1); Q = pcp: 2-(4-chloro-phenylazo)pyridine (strong π-acceptor), [2]+ bpy: 2,2′-bipyridyl (moderate π-acceptor), [3]+ acac-: acetylacetonate (strong σ-donor), 4; and DTBCat2-: 3,5-di-tert-butyl catecholate (strong π-donor), 5. The complexes [2]+, [3]+, 4, and 5 were fully characterized and structurally identified. The electronic structures of these complexes along with their redox partners were elucidated by using a host of physical measurements: nuclear magnetic resonance, cyclic voltammetry, electronic paramagnetic resonance, UV-vis-NIR spectroscopy, and density functional theory. The studies revealed significant effects of the coligands on azo bond lengths of the RuL moiety and their redox behavior. Aerobic alcohol oxidation reactions using these Ru complexes as catalysts were scrutinized. It was found that the catalytic efficiency is primarily controlled by the electronic effect of the coligand. Accordingly, the complex [2]+ (containing a strong π-acceptor coligand, pcp) brings about oxidation efficiently, producing 86% of benzaldehyde. In comparison, however, the complexes 4 and 5 (containing electron donating coligand) furnished only 15-20% of benzaldehyde under identical reaction conditions. Investigations of the reaction mechanism suggest that an unstable Ru-H species is formed, which is transformed to a Ru-hydrazo intermediate by H-walking as reported by Hall et al. (J. Am. Chem. Soc., 2015, 137, 12330). Aerial O2 regenerates the catalyst via oxidation of the hydrazo intermediate.
- Rath, Santi Prasad,Sengupta, Debabrata,Ghosh, Pradip,Bhattacharjee, Rameswar,Chakraborty, Mou,Samanta, Subhas,Datta, Ayan,Goswami, Sreebrata
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p. 11995 - 12009
(2018/09/25)
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- Effects of appended hydroxyl groups and ligand chain length on copper coordination and oxidation activity
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Treatment of a series of (imino)pyridine ligands bearing appended hydroxyl groups 2-((pyridin-2-ylmethylene)amino)phenol (Hpyph), 2-((pyridin-2-ylmethylene)amino)ethanol (Hpyet), and 3-((pyridin-2-ylmethylene)amino)propanol (Hpypr) with one equiv. of CuCl2·2H2O afforded the corresponding Cu(ii) complexes in low to moderate yields. The crystal structure of (μ-Cl)2[CuCl(κ2-N,N-Hpyet)]2 reveals a symmetric dinuclear structure with the bidentate N,N-coordination mode of (imino)pyridine with no Cu-OH interaction. On the other hand, the dinuclear Cu(ii) complex of the related propyl ligand Hpypr possesses a significantly different crystal structure involving nucleophilic addition of the hydroxyl group to the aldehyde group of 2-pyridinecarboxaldehyde. The Cu complex/Cu0/TEMPO/Na2CO3 (TEMPO = 2,2,6,6-tetramethylpiperidinyl-1-oxyl) catalyst system generally exhibited good activity for aerobic oxidation of benzyl alcohol to benzaldehyde in H2O at room temperature. The dinuclear Cu(ii) complex (μ-Cl)2[CuCl(κ2-N,N-Hpyet)]2 was demonstrated as an effective catalyst toward aerobic oxidation of various benzyl alcohol derivatives, cinnamyl alcohol, and 2-thiophenemethanol.
- Jehdaramarn, Attawit,Pornsuwan, Soraya,Chumsaeng, Phongnarin,Phomphrai, Khamphee,Sangtrirutnugul, Preeyanuch
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p. 654 - 661
(2017/12/28)
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- Synthetic method for organic synthesis intermediate 4-iodobenzaldehyde
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The invention discloses a synthetic method for the organic synthesis intermediate 4-iodobenzaldehyde. The synthetic method comprises the following steps: adding 2-amino-4-iodo-benzyl alcohol and a sodium sulfate solution into a reaction vessel, controlling a solution temperature and a stirring speed, carrying out a reaction, then adding an ethyl butyl ether solution, and continuing the reaction; and then adding 1,4-valerolactone solution, adding palladous nitrate powder in batches, raising the temperature after completion of the addition, controlling the stirring speed, carrying out a refluxing reaction, lowering the temperature, adding a potassium nitrate solution, carrying out standing, subjecting the obtained solution to layering, separating an oil layer, washing the oil layer with a sodium bromide solution at first and then with a N-ethylacetamide solution, carrying out recrystallization in a 2-aminoethanol solution, and then carrying out dehydration with a dehydrating agent to obtain the finished product 4-iodobenzaldehyde.
- -
-
Paragraph 0019-0020; 0023-0024; 0025-0028
(2018/07/30)
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- Studies on Iron-Catalyzed Aerobic Oxidation of Benzylic Alcohols to Carboxylic Acids
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A comprehensive study on aerobic oxidation of benzylic alcohols to carboxylic acids with a catalytic amount each of Fe(NO 3) 3 ·9H 2 O, TEMPO, and KCl is conducted. Various synthetically useful functional groups are well tolerated in the reaction. Distinct electronic and steric effects are observed in the reaction: electron-withdrawing groups accelerate the reaction while electron-donating groups make the reaction slower, and ortho -substituted substrates react slower than meta -substituted substrates. Several large-scale reactions (100 mmol) are conducted using a slow air flow of 30 mL/min to demonstrate the practicality of this method in an academic laboratory.
- Jiang, Xingguo,Ma, Shengming
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p. 1629 - 1639
(2018/02/26)
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- C-H Functionalization of N-Methylated Amino Acids and Peptides as Tool in Natural Product Synthesis: Synthesis of Abyssenine A and Mucronine e
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N-Methylated amino acids and peptides with an 8-aminoquinoline (AQ) directing group can be subjected to stereoselective Pd-catalyzed β-functionalizations. The best results are obtained with aryl iodides, but alkyl and alkenyl side chains can also be introduced. The AQ protecting group can easily be removed, providing the free carboxylic acid, which can be used directly in peptide couplings. This protocol was used successfully as a key step in the synthesis of the cyclopeptide alkaloids abyssenine A and mucronine E.
- Kinsinger, Thorsten,Kazmaier, Uli
-
supporting information
p. 7726 - 7730
(2018/12/11)
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- The facile approach to fabricate gold nanoparticles and their application on the hydration and dehydrogenation reactions
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A mild and practical strategy to prepare gold nanoparticles was developed. This gold particles supported mesoporous silica was fabricated from AuPPh3Cl under mild conditions and characterized through transmission electron microscopy, energy dispersive X-ray, X-ray power diffraction and X-ray photoelectron spectrometry. Interestingly, it was observed that this gold nanoparticle was effective to the hydration of alkynes and dehydrogenation of alcohols. The catalytic system can tolerate a variety of functional groups to afford the corresponding products in good to excellent yields.
- Huang, Ronghui,Fu, Yong,Zeng, Wei,Zhang, Liang,Wang, Dawei
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- Aerobic oxidation of benzyl alcohols to benzaldehydes using monoclinic bismuth vanadate nanoparticles under visible light irradiation: Photocatalysis selectivity and inhibition
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Monoclinic bismuth vanadate nanoparticles (nan-BiVO4) have been used for the selective photo-oxidation of benzyl alcohols (13 examples) to benzaldehydes under visible light irradiation using dioxygen as oxidant. Illumination with a blue LED (λmax = 470 nm) gave yields more than 30 times greater than bulk BiVO4 with >99% selectivity for several cases. Photo-oxidation of PhCH2OH/PhCD2OH isotopomers gave a kinetic isotope effect of 1.3 indicating that C–H bond activation is not the rate determining step in contrast to other reported photocatalysts including TiO2 and carbon nitride. Collectively, structural characterisation, spectroscopic, and reactivity data are correlated with the greater surface area of nan-BiVO4 compared to bulk BiVO4. Furthermore, conversion is shown to be limited as reaction progresses. Control experiments indicate that photo-oxidation is retarded by product aldehyde and that trace amounts (1%) of the corresponding benzoic acid, from over-oxidation, result in significant reduction in conversion.
- Unsworth, Christopher A.,Coulson, Ben,Chechik, Victor,Douthwaite, Richard E.
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p. 152 - 159
(2017/09/13)
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- Merging visible light photocatalysis of dye-sensitized TiO2 with TEMPO: The selective aerobic oxidation of alcohols
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The selective oxidation of alcohols to aldehydes or ketones is very difficult to accomplish when the oxidant is molecular oxygen (O2) and the reaction is carried out under ambient conditions. To meet these challenges, visible light photocatalysis was exploited to enable the use of O2 for the selective oxidation of alcohols at room temperature. In this scheme, eosin Y, an organic dye, was connected with TiO2 to capture visible light, leading to consequential photocatalytic processes. More importantly, these photocatalytic processes can be neatly merged with the redox catalytic cycles of TEMPO, which in turn induce the oxidation of alcohols under visible light irradiation. This work suggests that the merger of visible light photocatalysis and TEMPO catalysis has great potential for execution of challenging oxidative transformations.
- Zhang, Yichi,Wang, Zhan,Lang, Xianjun
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p. 4955 - 4963
(2017/11/09)
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- Method for synthesizing aromatic aldehyde, aromatic ketone and aromatic ester through catalytically oxidizing alkyl aromatic compound by iron
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The invention discloses a method for synthesizing aromatic aldehyde, aromatic ketone and aromatic ester through catalytically oxidizing an alkyl aromatic compound by iron, and belongs to the technical field of catalytic synthesis. According to the method, a low-cost and environment-friendly iron catalyst is used under a normal pressure; under the action of hydrogen and silicon reagents serving as an accelerant and an oxidant, a side chain of an aromatic hydrocarbon is oxidized into a carbonyl group for generating the corresponding aromatic aldehyde, aromatic ketone and aromatic ester. The method for preparing the aromatic aldehyde, the aromatic ketone and the aromatic ester through a catalytic oxidation reaction, which is provided by the invention, has numerous advantages that a catalyst, reaction raw materials, the oxidant and a silicon reagent are wide in sources and good in stability and is low-cost and environment-friendly; the alkyl aromatic compound is metered to participate in a reaction; the reaction condition is mild; the compatibility of functional groups is good; the scope of application is wide; the reaction selectivity is good; in an optimized reaction condition, the separation yield of a target product can be up to approximately 95 percent.
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Paragraph 0038; 0039
(2017/10/13)
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- One-pot two-step conversion of aromatic carboxylic acids and esters to aromatic aldehydes via indium-catalyzed reductive thioacetalization and desulfurization
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Described herein is that a new approach to a one-pot two-step conversion of aromatic carboxylic acids/esters to aromatic aldehydes, in which indium(III) iodide effectively catalyzes both the first reductive thioacetalization of carboxylic acids and a subsequent desulfurization of the in-situ formed thioacetal intermediates leading to aldehydes.
- Sakai, Norio,Minato, Kohei,Ogiwara, Yohei
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supporting information
p. 4563 - 4567
(2017/11/03)
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- Synthesis of Aldehydes by Organocatalytic Formylation Reactions of Boronic Acids with Glyoxylic Acid
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Reported herein is a conceptually novel organocatalytic strategy for the formylation of boronic acids. New reactivity is engineered into the α-amino-acid-forming Petasis reaction occurring between aryl boronic acids, amines, and glyoxylic acids to prepare aldehydes. The operational simplicity of the process and its ability to generate structurally diverse and valued aryl, heteroaryl, and α,β-unsaturated aldehydes containing a wide array of functional groups, demonstrates the practical utility of the new synthetic strategy.
- Huang, He,Yu, Chenguang,Li, Xiangmin,Zhang, Yongqiang,Zhang, Yueteng,Chen, Xiaobei,Mariano, Patrick S.,Xie, Hexin,Wang, Wei
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supporting information
p. 8201 - 8205
(2017/06/30)
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- Hydroxyl Radicals via Collision-Induced Dissociation of Trimethylammonium Benzyl Alcohols
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The hydroxyl radical is a well known reactive oxygen species important for interstellar, atmospheric, and combustion chemistry in addition to multiple biochemical processes. Although there are many methods to generate the hydroxyl radical, most of these are inorganic based, with only a few originating from organic precursor molecules. Reported herein is the observation that trimethylammonium benzyl alcohols and their corresponding deuterated isotopologues act as a good source of hydroxyl and deuteroxyl radicals in the gas-phase under collision-induced dissociation (CID) conditions. Attempts to replicate this chemistry in the condensed phase are described.
- Moore, Peter W.,Hooker, Jordan P.,Zavras, Athanasios,Khairallah, George N.,Krenske, Elizabeth H.,Bernhardt, Paul V.,Quach, Gina,Moore, Evan G.,O'Hair, Richard A. J.,Williams, Craig M.
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p. 397 - 406
(2017/04/07)
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- Simple and Efficient Ruthenium-Catalyzed Oxidation of Primary Alcohols with Molecular Oxygen
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Oxidative transformations utilizing molecular oxygen (O2) as the stoichiometric oxidant are of paramount importance in organic synthesis from ecological and economical perspectives. Alcohol oxidation reactions that employ O2are scarce in homogeneous catalysis and the efficacy of such systems has been constrained by limited substrate scope (most involve secondary alcohol oxidation) or practical factors, such as the need for an excess of base or an additive. Catalytic systems employing O2as the “primary” oxidant, in the absence of any additive, are rare. A solution to this longstanding issue is offered by the development of an efficient ruthenium-catalyzed oxidation protocol, which enables smooth oxidation of a wide variety of primary, as well as secondary benzylic, allylic, heterocyclic, and aliphatic, alcohols with molecular oxygen as the primary oxidant and without any base or hydrogen- or electron-transfer agents. Most importantly, a high degree of selectivity during alcohol oxidation has been predicted for complex settings. Preliminary mechanistic studies including18O labeling established the in situ formation of an oxo–ruthenium intermediate as the active catalytic species in the cycle and involvement of a two-electron hydride transfer in the rate-limiting step.
- Ray, Ritwika,Chandra, Shubhadeep,Maiti, Debabrata,Lahiri, Goutam Kumar
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supporting information
p. 8814 - 8822
(2016/07/06)
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- Environmentally friendly procedure for the aqueous oxidation of benzyl alcohols to aldehydes with dibromodimethylhydantoin (DBDMH) and cyclodextrin: Scope and mechanistic insights
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Reported herein is an environmentally friendly procedure for the oxidation of benzyl alcohols to aldehydes using an inexpensive, commercially available reagent, 1,3-dibromo-5,5-dimethylhydantoin (DBDMH), and a variety of cyclodextrin additives under fully aqueous solvent conditions. This reaction proceeds with moderate to good yields for a broad scope of benzyl alcohol substrates, with the cyclodextrin acting to enhance the desired reactivity and limit undesired aromatic bromination side products. The reported experiments provide substantial mechanistic insight that will drive further reaction optimization and have broad-reaching applications.
- Chaudhuri, Sauradip,Zaki, Hossam,Levine, Mindy
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p. 636 - 644
(2016/06/06)
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- Electronic Structure and Multicatalytic Features of Redox-Active Bis(arylimino)acenaphthene (BIAN)-Derived Ruthenium Complexes
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The article examines the newly designed and structurally characterized redox-active BIAN-derived [Ru(trpy)(R-BIAN)Cl]ClO4 ([1a]ClO4-[1c]ClO4), [Ru(trpy)(R-BIAN)(H2O)](ClO4)2 ([3a](ClO4)2-[3c](ClO4)2), and BIAO-derived [Ru(trpy)(BIAO)Cl]ClO4 ([2a]ClO4) (trpy = 2,2′:6′,2′′-terpyridine, R-BIAN = bis(arylimino)acenaphthene (R = H (1a+, 3a2+), 4-OMe (1b+, 3b2+), 4-NO2 (1c+, 3c2+), BIAO = [N-(phenyl)imino]acenapthenone). The experimental (X-ray, 1H NMR, spectroelectrochemistry, EPR) and DFT/TD-DFT calculations of 1an-1cn or 2an collectively establish {RuII-BIAN0} or {RuII-BIAO0} configuration in the native state, metal-based oxidation to {RuIII-BIAN0} or {RuIII-BIAO0}, and successive electron uptake processes by the α-diimine fragment, followed by trpy and naphthalene π-system of BIAN or BIAO, respectively. The impact of the electron-withdrawing NO2 function in the BIAN moiety in 1c+ has been reflected in the five nearby reduction steps within the accessible potential limit of -2 V versus SCE, leading to a fully reduced BIAN4- state in [1c]4-. The aqua derivatives ({RuII-OH2}, 3a2+-3c2+) undergo simultaneous 2e-/2H+ transfer to the corresponding {RuIV-O} state and the catalytic current associated with the RuIV/RuV response probably implies its involvement in the electrocatalytic water oxidation. The aqua derivatives (3a2+-3c2+) are efficient and selective precatalysts in transforming a wide variety of alkenes to corresponding epoxides in the presence of PhI(OAc)2 as an oxidant in CH2Cl2 at 298 K as well as oxidation of primary, secondary, and heterocyclic alcohols with a large substrate scope with H2O2 as the stoichiometric oxidant in CH3CN at 343 K. The involvement of the {RuIV-O} intermediate as the active catalyst in both the oxidation processes has been ascertained via a sequence of experimental evidence.
- Singha Hazari, Arijit,Ray, Ritwika,Hoque, Md Asmaul,Lahiri, Goutam Kumar
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p. 8160 - 8173
(2016/08/24)
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- Visible light photocatalysis with CBr4: A highly selective aerobic photooxidation of methylarenes to aldehydes
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A metal-free, operationally simple and efficient means of aerobic photooxidation of methylarenes to aromatic aldehydes at room temperature employing visible light photocatalysis with CBr4 is reported. The reaction is highly selective as it proceeds without any over oxidation to carboxylic acids. The utilisation of visible light and molecular oxygen is inexpensive, readily available, non-toxic and the sustainable reagents make the protocol compatible with green chemistry demands. A plausible mechanism for the formation of aldehydes from methylarenes is also provided.
- Tripathi, Shubhangi,Singh, Sachchida N.,Yadav, Lal Dhar S.
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p. 14547 - 14551
(2016/02/19)
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- A practical and general ipso iodination of arylboronic acids using N-iodomorpholinium iodide (NIMI) as a novel iodinating agent: mild and regioselective synthesis of aryliodides
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A mild and efficient protocol for the ipso-iodination of aryl boronic acids using N-iodomorpholinium iodide (NIMI) generated in situ from morpholine and molecular iodine as a novel iodinating agent has been developed. The addition of a catalytic amount of copper iodide found to promote rate enhancement of the iodination reaction and dramatic increase in the yield depending upon the nature of the boronic acid was observed. The mechanistic study revealed that depending upon the nature of the substrate, either the classical ipso substitution or copper catalysed iododeborylation pathway overall dominates the present iodination reaction. The features such as mild reaction conditions, operational simplicity, high to excellent yields, excellent functional group compatibility and low catalyst loading make this method potentially useful in organic synthesis.
- Tale,Toradmal,Gopula
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p. 84910 - 84919
(2015/10/28)
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