- 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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- 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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supporting information
p. 3583 - 3588
(2020/08/05)
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- Cyclopentadienyl Ruthenium(II) Complex-Mediated Oxidation of Benzylic and Allylic Alcohols to Corresponding Aldehydes
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This work reports an efficient method for the oxidation reaction of aliphatic, aromatic allylic, and benzylic alcohols into aldehydes catalyzed by the cyclopentadienyl ruthenium(II) complex (RuCpCl(PPh3)2) with bubbled O2. Through further optimizing controlled studies, the tendency order of oxidation reactivity was determined as follows: benzylic alcohols > aromatic allylic alcohols >> aliphatic alcohols. In addition, this method has several advantages, including a small amount of catalyst (0.5 mol%) and selective application of high discrimination activity of aliphatic, aromatic allylic, and benzylic alcohols.
- Chern, Ching-Yuh,Tseng, Ching-Chun,Hsiao, Rong-Hong,Wong, Fung Fuh,Kuo, Yueh-Hsiung
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- Mild, Redox-Neutral Formylation of Aryl Chlorides through the Photocatalytic Generation of Chlorine Radicals
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We report a redox-neutral formylation of aryl chlorides that proceeds through selective 2-functionalization of 1,3-dioxolane through nickel and photoredox catalysis. This scalable benchtop approach provides a distinct advantage over traditional reductive carbonylation in that no carbon monoxide, pressurized gas, or stoichiometric reductant is employed. The mild conditions give unprecedented scope from abundant and complex aryl chloride starting materials.
- Nielsen, Matthew K.,Shields, Benjamin J.,Liu, Junyi,Williams, Michael J.,Zacuto, Michael J.,Doyle, Abigail G.
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supporting information
p. 7191 - 7194
(2017/06/13)
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- Selectivity Modulation of the Ley–Griffith TPAP Oxidation with N-Oxide Salts
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A wide variety of novel non-hygroscopic N-oxide tetraphenylborate salts were synthesized and evaluated as co-oxidants in the Ley–Griffith (TPAP) oxidation of benzylic and allylic alcohols under non-anhydrous conditions. The novel DABCOO·TPB (2:1) salt was herein unearthed as a viable competitor to the first-generation NMO·TPB (2:1) salt, but more importantly gave increased performance under oxidative competition. X-ray crystal structure analysis and NMR spectroscopy revealed that depending on the crystallization conditions 1:1, 2:1 or 3:2 N-oxide–tetraphenylborate salts could be formed.
- Moore, Peter W.,Jiao, Yanxiao,Mirzayans, Paul M.,Sheng, Lexter Ng Qi,Hooker, Jordan P.,Williams, Craig M.
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p. 3401 - 3407
(2016/07/26)
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- Synthetic utility of iodic acid in the oxidation of benzylic alcohols to aromatic aldehydes and ketones
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Various primary and secondary benzylic alcohols were efficiently oxidized to aromatic aldehydes and aromatic ketones with iodic acid in DMF at 60?°C for 2?h and with iodic acid in the presence of TEMPO (5?mol?%) in DMF at room temperature, respectively. The former method was effective for the oxidation of sterically hindered alcohols at 60?°C and the latter method was effective for the oxidation of less sterically hindered alcohols at room temperature.
- Imai, Sho,Togo, Hideo
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p. 6948 - 6954
(2016/10/13)
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- Photoredox removal of p-methoxybenzyl ether protecting group with hydrogen peroxide as terminal oxidant
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We report a mild protocol for removal of the p-methoxybenzyl ether protecting group under acidic conditions with eosin Y combined with LEDs as a photoredox catalysis system and hydrogen peroxide as the terminal oxidant. This protocol is compatible with ethers derived from primary, secondary, and tertiary alcohols, as well as with various functional groups. The protocol showed unusual selectivity for a tertiary ether over a primary ether. The scale up to gram scale is also explored and identical reactivity is observed.
- Liu, Zheng,Zhang, Yi,Cai, Zheren,Sun, Hao,Cheng, Xu
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p. 589 - 593
(2015/03/05)
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- Fluorous bispidine: A bifunctional reagent for copper-catalyzed oxidation and knoevenagel condensation reactions in water
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Fluorous bispidine-type ligands have been developed to facilitate its recovery and reusability and to demonstrate its bifunctional property as a ligand and base in copper-catalyzed aerobic oxidation, the Knoevenagel condensation and tandem oxidation/Knoevenagel condensation in water under mild conditions. Application of the fluorous ligand was also extended to the surfactant-free copper-catalyzed allylic and benzylic sp3 C-H oxidation reaction in water. The fluorous ligands could be recovered using F-SPE with recovery ranging from 91-97% and could be reused five times with little loss of activity.
- Ang, Wei Jie,Chng, Yong Sheng,Lam, Yulin
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p. 81415 - 81428
(2015/10/06)
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- NMO·TPB: A selectivity variation on the Ley-Griffith TPAP oxidation
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A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO·TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.
- Moore, Peter W.,Mirzayans, Paul M.,Williams, Craig M.
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supporting information
p. 3567 - 3571
(2015/03/04)
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- Selective oxidations of activated alcohols in water at room temperature
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Allylic and benzylic alcohols can be selectively oxidized to their corresponding aldehydes or ketones in water containing nanoreactors composed of the designer surfactant TPGS-750-M. The oxidation relies on catalytic amounts of CuBr, bpy, and TEMPO, with N-methyl-imidazole; air is the stoichiometric oxidant. the Partner Organisations 2014.
- Lipshutz,Hageman,Fennewald,Linstadt,Slack,Voigtritter
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supporting information
p. 11378 - 11381
(2014/11/08)
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- Mild oxidation of benzylic amines into aldehydes using an oxidative Polonovski-like process
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A chemoselective and environmentally benign oxidation of benzylic amines into aldehydes mediated by a hypervalent iodine reagent has been developed. This mild oxidative version of the Polonovski process may be selectively carried out in the presence of several functionalities including a free alcohol and provides new synthetic opportunities as a masked aldehyde segment. Georg Thieme Verlag Stuttgart · New York.
- Desjardins, Samuel,Jacquemot, Guillaume,Canesi, Sylvain
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experimental part
p. 1497 - 1500
(2012/07/28)
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- NOVEL THIOPHENE DERIVATIVES AS SPHINGOSINE-1-PHOSPHATE-1 RECEPTOR AGONISTS
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The invention relates to novel thiophene derivatives, their preparation and their use as pharmaceutically active compounds. Said compounds particularly act as immunosuppressive agents.
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- Novel Thiophene Derivatives as Spingosine-1-Phosphate-1 Receptor Agonists
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The invention relates to novel thiophene derivatives, their preparation and their use as pharmaceutically active compounds. Said compounds particularly act as immunosuppressive agents.
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Page/Page column 21
(2008/12/07)
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- FUSED HETEROCYCLIC DERIVATIVE, MEDICINAL COMPOSITION CONTAINING THE SAME, AND MEDICINAL USE THEREOF
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The present invention provides fused heterocyclic derivatives represented by the general formula: wherein R1 represents H, halogen, OH, etc.; R2 represents H, halogen or an alkyl group; R3 and R4 represent H, OH, halogen, etc.; Q represents alkylene, etc.; ring A represents aryl or heteroaryl; and G represents or ???or pharmaceutically acceptable salts thereof, or prodrugs thereof, which exhibit an excellent inhibitory activity in human SGLT and are useful as agents for the prevention or treatment of a disease associated with hyperglycemia such as diabetes, postprandial hyperglycemia, impaired glucose tolerance, diabetic complications or obesity, pharmaceutical compositions comprising the same, and pharmaceutical uses thereof.
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Page/Page column 64
(2008/06/13)
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- Radical isomerization via intramolecular ipso substitution of aryl ethers: Aryl translocation from oxygen to carbon
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Bromopropyl aryl ethers an converted to 3-arylpropanols under standard radical generating conditions in the presence of tributylstannane and AIBN. This rearrangement involves intramolecular ipso attack of the alkyl radicals which generates spiro cyclohexadienyl radical intermediates.
- Lee, Eun,Lee, Chulbom,Tae, Jin Sung,Whang, Ho Sung,Li, Kap Sok
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p. 2343 - 2346
(2007/10/02)
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- 5-Arylidene 1,3-Dimethylbarbituric Acid Derivatives, Mild Organic Oxidants for Allylic and Benzylic Alcohols
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Various 5-arylidene 1,3-dimethylbarbituric acid derivatives and closely related compounds were synthesized as models of redox coenzymes and used for oxidation of alcohols.Under mild neutral conditions, 5-arylidene 1,3-dimethylbarbituric acid derivatives, especially those having an electron-withdrawing group on the aromatic ring, effectively oxidized allylic and benzylic alcohols to the corresponding carbonyl compounds.The relationship between the oxidizing ability and the structure of the oxidant (coenzyme model) was investigated and it was found that the electron density on the carbon-carbon double bond is a critical factor for the oxidation.In the case of the deuterium-labeled compound, the observed value of normal and primary isotope effect was 3.3 and so it was concluded that mechanism of this oxidation mainly involves the hydride transfer from the alcohol.An electrochemical investigation was also carried out and the redox potentials of the coenzyme models, 5-arylidene 1,3-dimethylbarbituric acid derivatives and related compounds, were measured.Keywords - 5-arylidene 1,3-dimethylbarbituric acid; coenzyme model; oxidation; allylic alcohol; benzylic alcohol; oxidation mechanism; hydride transfer; primary isotope effect; cyclic voltammetry; redox potential
- Tanaka, Kiyoshi,Chen, Xing,Kimura, Teiji,Yoneda, Fumio
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- Imidazolium Dichromate. A New Reagent for the Oxidation of Alcohols to Carbonyl Compounds
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Imidazolium dichromate, a stable yellow crystalline compound, is found to bee a mild selective reagent for the oxidation of allylic and benzylic alcohols to the corresponding carbonyl compounds.
- Kim, Sunggak,Lhim, Dong Chul
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p. 3297 - 3298
(2007/10/02)
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- CERIUM(IV) AMMONIUM NITRATE-CHARCOAL SYSTEM. AN EFFECTIVE CATALYST FOR THE AIR OXIDATION OF BENZYL ALCOHOLS AND ACYLOINS
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Cerium(IV) ammonium nitrate (CAN) adsorbed on activated charcoal has been found to be an effective catalyst for the air oxidation of benzyl alcohols and acyloins to the corresponding carbonyl compounds.
- Hatanaka, Yasuo,Imamoto, Tsuneo,Yokoyama, Masataka
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p. 2399 - 2400
(2007/10/02)
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- 4-(Dimethylamino)pyridinium Chlorochromate, a New Selective Reagent for the Oxidation of Allylic and Benzylic Alcohols
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4-(Dimethylamino)pyridinium chlorochromate (3) is a mild selective reagent for the oxidation of complex allylic and benzylic alcohols to the corresponding carbonyl compounds.
- Guziec, Frank S.,Luzzio, Frederick A.
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p. 1787 - 1789
(2007/10/02)
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