- Electrochemical Oxidation of Alcohols and Aldehydes to Carboxylic Acids Catalyzed by 4-Acetamido-TEMPO: An Alternative to "anelli" and "pinnick" Oxidations
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An electrocatalytic method has been developed to oxidize primary alcohols and aldehydes to the corresponding carboxylic acids using 4-acetamido-2,2,6,6-tetramethylpiperidin-1-oxyl (ACT) as a mediator. The method successfully converts benzylic, aliphatic, heterocyclic, and other heteroatom-containing substrates to the corresponding carboxylic acids in aqueous solution at room temperature. The mild conditions enable retention of stereochemistry adjacent to the site of oxidation, as demonstrated in a 40 g-scale synthesis of a precursor to levetiracetam, a medication used to treat epilepsy.
- Rafiee, Mohammad,Konz, Zachary M.,Graaf, Matthew D.,Koolman, Hannes F.,Stahl, Shannon S.
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p. 6738 - 6744
(2018/06/19)
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- Aerobic Oxidation of Diverse Primary Alcohols to Carboxylic Acids with a Heterogeneous Pd-Bi-Te/C (PBT/C) Catalyst
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Heterogeneous catalytic aerobic oxidation methods represent a near-ideal approach for the conversion of primary alcohols to carboxylic acids. Here, we report that a heterogeneous catalyst composed of Pd, Bi, and Te supported on activated carbon is highly effective for the oxidation of diverse benzylic and aliphatic primary alcohols, including 5-(hydroxymethyl)furfural (HMF) and substrates bearing heterocycles and other important functional groups. In many cases, the desired carboxylic acid product is obtained in >90% yield. Additionally, the catalyst has been demonstrated in a continuous-flow packed-bed reactor for the oxidation of benzyl alcohol, achieving near-quantitative yield while undergoing over 30 000 turnovers.
- Ahmed, Maaz S.,Mannel, David S.,Root, Thatcher W.,Stahl, Shannon S.
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supporting information
p. 1388 - 1393
(2017/09/22)
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- QUINOLINE DERIVATIVES
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The invention relates to quinoline compounds of the formula (I) and/or pharmaceutically acceptable salts and/or solvates thereof, wherein Y, W, U, Q, R1, R5 R7 and R30 are as defined in the description. Such compounds are suitable for the treatment of a disorder or disease which is mediated by the activity of the PI3K enzymes.
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Page/Page column 100; 101
(2013/07/05)
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- Highly efficient rhodium catalysts for the asymmetric hydroformylation of vinyl and allyl ethers using C1-symmetrical diphosphite ligands
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Here, we describe the successful application of novel glucofuranose-derived 1,3-diphosphites in the rhodium-catalysed asymmetric hydroformylation of vinyl acetate, 2,5-dihydrofuran and 2,3-dihydrofuran. In the hydroformylation of vinyl acetate, total regioselectivity and high ee (up to 73%) were obtained. When 2,3- and 2,5-dihydrofuran were the substrates, total chemo- and regioselectivities were achieved together with ees up to 88%. These results correspond to the highest ee values reported to date in the asymmetric hydroformylation of these substrates. The HP-NMR studies of the [RhH(CO) 2(L)] species (L=15 and 17) demonstrated that both ligands coordinate to the Rh centre in an eq-eq fashion. The complex [RhH(CO)2(15)] was detected as a single isomer with characteristic features of eq-eq coordination. However, the broadening of the corresponding signals indicated that this species is rapidly interchanging in solution. In contrast, complex [RhH(CO) 2(17)] was detected as a mixture of two conformational isomers at low temperature due to the greater flexibility of the monocyclic backbone of this ligand.
- Gual, Aitor,Godard, Cyril,Castillon, Sergio,Claver, Carmen
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experimental part
p. 463 - 477
(2010/06/13)
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- Tempo-mediated oxidation of primary alcohols to carboxylic acids by exploitation of ethers inan aqueous-organicbiphase system
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Expeditious and benign methods for primary alcohol- carboxylicacid conversions with TEMPO were developed in abiphasic system composed of aslightlymiscible ether (THP) and aqueous layer. Easily available co-oxidants such as Py-HBr3, Bu4NBr3, and electrooxidation were successfully applied to generate N-oxoammonium species as a recyclable catalyst.
- Mei, Zhen-Wu,Ma, Li-Jian,Kawafuchi, Hiroyuki,Okihara, Takumi,Inokuchi, Tsutomu
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experimental part
p. 1000 - 1002
(2011/03/22)
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- Preparation of tetrahydro-3-furoic acid
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Disclosed is a process for the preparation of tetrahydro-3-furoic acid by the thermal, non-catalytic oxidation of 3-formyltetrahydrofuran using molecular oxygen.
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Page/Page column 3-5
(2008/06/13)
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- Chiral heterospirocylic 2H-azirin-3-amines as synthons for 3-amino-2,3,4,-tetrahydrofuran-3-carboxylic acid and their use in peptide synthesis
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The heterospirocyclic N-methyl-N-phenyl-5-oxa-1-azaspiro[2.4]hept-1-e n-2-amine (6) and N-(5-oxa-1-azaspiro[2.4]hept-1-en-2-yl)-(S)-proline methyl ester (7) were synthesized from the corresponding heterocyclic thiocarboxamides 12 and 10, respectively, by consecutive treatment with COCl2, 1,4-diazabicyclo[2.2.2]octane, and NaN3 (Schemes 1 and 2). The reaction of these 2H-azirin-3-amines with thiobenzoic and benzoic acid gave the racemic benzamides 13 and 14, and the diastereoisomeric mixtures of the N-benzoyl dipeptides 15 and 16, respectively (Scheme 3). The latter were separated chromatographically. The configurations and solid-state conformations of all six henzamides were determined by X-ray crystallography. With the aim of examining the use of the new synthons in peptide synthesis the reactions of 7 with Z-Leu-Aib-OH to yield a tetrapeptide 17 (Scheme 4), and of 6 with Z-Ala-OH to give a dipeptide 18 (Scheme 5) were performed. The resulting diastereoisomers were separated by means of MPLC or HPLC. NMR Studies of the solvent dependence of the chemical shifts of the NH resonances indicate the presence of an intramolecular H-bond in 17. The dipeptides (S,R)-18 and (S,S)-18 were deprotected at the N-terminus and were converted to the crystalline derivatives (S,R)-19 and (S,S)-19, respectively, by reaction with 4-bromobenzoyl chloride (Scheme 5). Selective hydrolysis of (SR)-18 and (S.S)-18 gave the dipeptide acids (R,S)-20 and (SS)-20, respectively. Coupling of a diastereoisomeric mixture of 20 with H-Phe-O′Bu led to the tripeptides 21 (Scheme 5). X-Ray crystal-structure determinations of (S,R)-19 and (S,S)-19 allowed the determination of the absolute configurations of all diastereoisomers isolated in this series.
- Stamm, Simon,Linden, Anthony,Heimgartner, Heinz
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p. 1371 - 1396
(2007/10/03)
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- Pyrazolo-[1,5-a]-1,3,5-triazine corticotropin-releasing factor (CRF) receptor ligands
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The syntheses and rat CRF receptor binding affinities of 'retro-pyrazolotriazine' corticotropin-releasing factor (CRF) ligands 4 are reported. Some have high affinity for rat CRF receptors (Ki≤10 nM). The data provide additional support for the hypothesis that it is possible to interchange isosteric cores with similar electronic properties in the design of high-affinity CRF receptor ligands, provided the peripheral pharmacophore elements are maintained in the same three-dimensional array.
- Gilligan, Paul J.,Folmer, Beverly K.,Hartz, Richard A.,Koch, Stephanie,Nanda, Kausik K.,Andreuski, Stephen,Fitzgerald, Lawrence,Miller, Keith,Marshall, William J.
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p. 4093 - 4102
(2007/10/03)
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- An improved and practical sharpless oxidation of primary alcohols to the carboxylic acids
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An improved and practical procedure for the oxidation of primary alcohols to the carboxylic acids under Sharpless's conditions (NaIO4/RuCl3.H2O/water/acetonitrile) using ethyl acetate as the solvent, in place of toxic and ecologically undesirable carbon tetrachloride, is described.
- Prashad, Mahavir,Lu, Yansong,Kim, Hong-Yong,Hu, Bin,Repic, Oljan,Blacklock, Thomas J.
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p. 2937 - 2942
(2007/10/03)
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- STRUCTURE AND FORMATION OF C4H7O(1+) IONS RESULTING FROM ELECTRON IMPACT INDUCED DECOMPOSITION OF CYCLIC PRECURSORS
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Possible structures and modes of formation of C4H7O(1+) ions formed by electron impact induced decomposition of tetrahydrofuran and tetrahydropyran derivates are discussed in view of labelling results and MIKE, CA, and T data.Limitations of these techniques are pointed out.
- Stolze, Rainer,Budzikiewicz, Herbert
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p. 781 - 787
(2007/10/02)
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