- Group 6 Metal Carbonyl Complexes Supported by a Bidentate PN Ligand: Syntheses, Characterization, and Catalytic Hydrogenation Activity
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We report on the preparation of a series of phosphorus-nitrogen donor ligand complexes [M(CO)4(PN)], where M = Cr, Mo, W and PN is 2-(diphenylphosphino)ethylamine. The organometallic compounds were readily obtained upon reacting the respective metal hexacarbonyls with equimolar amounts of the pertinent ligand in the presence of tetraethylammonium bromide. The PN-ligated metal carbonyls were fully characterized by standard spectroscopic techniques and X-ray crystallography. The ability of the title compounds to function as homogeneous hydrogenation catalysts was probed in the reduction of acetophenone and benzaldehyde derivatives to yield the corresponding alcohols. The reaction setup was easily assembled by simply combining the components in the autoclave on the bench outside an inert-gas-operated glovebox system.
- Faust, Kirill,Topf, Christoph,Vielhaber, Thomas
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p. 4535 - 4543
(2020/12/23)
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- Expanding the Substrate Specificity of Thermoanaerobacter pseudoethanolicus Secondary Alcohol Dehydrogenase by a Dual Site Mutation
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Here, we report the asymmetric reduction of selected phenyl-ring-containing ketones by various single- and dual-site mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). The further expansion of the size of the substrate binding pocket in the mutant W110A/I86A not only allowed the accommodation of substrates of the single mutants W110A and I86A within the expanded active site but also expanded the substrate range of the enzyme to ketones bearing two sterically demanding groups (bulky–bulky ketones), which are not substrates for the TeSADH single mutants. We also report the regio- and enantioselective reduction of diketones with W110A/I86A TeSADH and single TeSADH mutants. The double mutant exhibited dual stereopreference to generate the Prelog products most of the time and the anti-Prelog products in a few cases.
- Musa, Musa M.,Bsharat, Odey,Karume, Ibrahim,Vieille, Claire,Takahashi, Masateru,Hamdan, Samir M.
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p. 798 - 805
(2018/02/21)
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- A Straightforward Deracemization of sec-Alcohols Combining Organocatalytic Oxidation and Biocatalytic Reduction
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An efficient organocatalytic oxidation of racemic secondary alcohols, mediated by sodium hypochlorite (NaOCl) and 2-azaadamantane N-oxyl (AZADO), has been conveniently coupled with a highly stereoselective bioreduction of the intermediate ketone, catalyzed by ketoreductases, in aqueous medium. The potential of this one-pot two-step deracemization process has been proven by a large set of structurally different secondary alcohols. Reactions were carried out up to 100 mm final concentration enabling the preparation of enantiopure alcohols with very high isolated yields (up to 98 %). When the protocol was applied to the stereoisomeric rac/meso mixture of diols, these were obtained with very high enantiomeric excesses and diastereomeric ratios (95 % yield, >99 % ee, >99: 1 dr).
- Liardo, Elisa,Ríos-Lombardía, Nicolás,Morís, Francisco,González-Sabín, Javier,Rebolledo, Francisca
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supporting information
p. 3031 - 3035
(2018/06/27)
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- Nickel-Catalyzed C-Alkylation of Nitroalkanes with Unactivated Alkyl Iodides
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Enabled by nickel catalysis, a mild and general catalytic method for C-alkylation of nitroalkanes with unactivated alkyl iodides is described. Compatible with primary, secondary, and tertiary alkyl iodides; and tolerant of a wide range of functional groups, this method allows rapid access to diverse nitroalkanes.
- Rezazadeh, Sina,Devannah, Vijayarajan,Watson, Donald A.
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supporting information
p. 8110 - 8113
(2017/06/28)
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- Unveiling the Hidden Performance of Whole Cells in the Asymmetric Bioreduction of Aryl-containing Ketones in Aqueous Deep Eutectic Solvents
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In this contribution, we report the first successful baker's yeast reduction of arylpropanones using deep eutectic solvents (DESs) as biodegradable and non-hazardous co-solvents. The nature of DES [e.g. choline chloride/glycerol (2:1)] and the percentage of water in the mixture proved to be critical for both the reversal of selectivity and to achieve high enantioselectivity on going from pure water (up to 98:2 er in favour of the S-enantiomer) to DES/aqueous mixtures (up to 98:2 er in favour of the R-enantiomer). As a result, both enantiomers of valuable chiral alcohols of pharmaceutical interest were prepared from the same biocatalyst by simply switching the solvent. The possible inhibition of some (S)-oxidoreductases making part of the genome of such a wild-type whole cell biocatalyst when DESs are used as co-solvents may pave the way for an anti-Prelog reduction. The scope and limitations of this kind of biotransformations for a range of aryl-containing ketones are also discussed. (Figure presented.).
- Vitale, Paola,Abbinante, Vincenzo Mirco,Perna, Filippo Maria,Salomone, Antonio,Cardellicchio, Cosimo,Capriati, Vito
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supporting information
p. 1049 - 1057
(2017/03/31)
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- Facile Protocol for Catalytic Frustrated Lewis Pair Hydrogenation and Reductive Deoxygenation of Ketones and Aldehydes
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A series of ketones and aldehydes are reduced in toluene under H2 in the presence of 5 mol % B(C6F5)3 and either cyclodextrin or molecular sieves affording a facile metal-free protocol for reduction to alcohols. Similar treatment of aryl ketones resulted in metal-free deoxygenation yielding aromatic hydrocarbons.
- Mahdi, Tayseer,Stephan, Douglas W.
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supporting information
p. 8511 - 8514
(2015/11/27)
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- Enabling catalytic ketone hydrogenation by frustrated lewis pairs
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Hydrogenation of alkyl and aryl ketones using H2 is catalytically achieved in 18 examples using 5 mol % B(C6F5)3 in an ethereal solvent. In these cases the borane and ether behave as a frustrated Lewis pair to activate H2 and effect the reduction.
- Mahdi, Tayseer,Stephan, Douglas W.
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supporting information
p. 15809 - 15812
(2015/02/19)
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- Ether-directed ortho-C-H olefination with a palladium(II)/monoprotected amino acid catalyst
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Weak coordination is powerful! A PdII-catalyzed olefination of ortho-C-H bonds of arenes directed by weakly coordinating ethers is developed by using monoprotected amino acid (MPAA) ligands. This finding provides a method for chemically modifying ethers, which are abundant in natural products and drug molecules. HFIP=hexafluoroisopropanol. Copyright
- Li, Gang,Leow, Dasheng,Wan, Li,Yu, Jin-Quan
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supporting information
p. 1245 - 1247
(2013/03/13)
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- Screening on the use of Kluyveromyces marxianus CBS 6556 growing cells as enantioselective biocatalysts for ketone reductions
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The versatility of Kluyveromyces marxianus CBS 6556 growing cells in the enantioselective reduction of ketone functionalities to the corresponding alcohols was exploited. In particular, methyl ketones were reduced to (S)-alcohols with ees of up to 96%. Longer chain alkyl ketones afforded, under the same experimental condition, (R)-alcohols with an ee of up to 84%. Interestingly, carbon-carbon double and the triple bonds can also be reduced in the presence of Kluyveromyces marxianus CBS 6556 yeast. A cyclic ketone, such as 2-tetralone, was also quantitatively reduced to its corresponding (S)-alcohol with ee = 76%.
- Vitale, Paola,Perna, Filippo Maria,Perrone, Maria Grazia,Scilimati, Antonio
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body text
p. 1985 - 1993
(2012/03/22)
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- Homochiral (R)- and (S)-1-heteroaryl- and 1-aryl-2-propanols via microbial redox
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Preparation of various heteroaryl propanols 2a-g and of the corresponding propanones 3a-g as starting materials for microbial redox is described. The kinetic resolution of the racemic propanols 2a-g is obtained via oxidation with Pseudomonas paucimobilis and Bacillus stearothermophilus [(R)-alcohols, ee 74-100%]. Similar results are achieved with 3-(2- hydroxypropyl)trifluoromethylbenzene 7 (44%, ee 100% of the (R)-alcohol 6). The reduction of the propanones 3a-d and 3g with baker's yeast and other fungi gives the (S)-alcohols (ee 100%). The pure (S)-alcohols are also obtained by reduction of 1-[3-(trifluoromethyl)phenyl]-2-propanone 7. 1- [(4,4-Dimethyl)-2-(Δ2)oxazolinyl]-2-propanone 3e and 1[2-(Δ2)- thiazolinyl)-2-propanone 3f are not reduced. The heterocyclic rings of (S)- 5-(2-hydroxypropyl)-3-methylisoxazole 2d and of (S)-2-(2-hydroxypropyl)-4- methylthiazole 2g are deblocked to the homochiral enamino ketone 8 (78%) and to the protected β-hydroxy aldehyde 9 (73%), respectively. The (R)-3-(2- hydroxypropyl)trifluoromethylbenzene 6 is transformed into the homochiral precursor of (S)-fenfluramine 10 (overall yield 65%).
- Fogagnolo, Marco,Giovannini, Pier Paolo,Guerrini, Alessandra,Medici, Alessandro,Pedrini, Paola,Colombi, Nicola
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p. 2317 - 2327
(2007/10/03)
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- Behavior and extension of the scope of NADH models to the reduction of non-activated ketones by a stable indolo NADH model compound in the presence of Lewis acids
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The reduction of non-activated ketones, eg, acetophenone, by a very stable NADH model in the presence of Lewis acids (AlX3, Et2AlCl) is reported.During the reaction, a side equilibrated aldol condensation occurs.Due to the reversibility of this reaction, the overall yield in alcohol is not notably diminished.The scope of NADH models has been extended for the first time to non-activated ketones, such as dialkyl, aryl alkyl and diaryl ketones. - Keywords: NADH model / ketone reduction / Lewis acids / aldol condensation
- Berkous, Rabia,Dupas, Georges,Bourguignon, Jean,Queguiner, Guy
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p. 632 - 635
(2007/10/02)
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- Asymmetric syntheses of (S)-Fenfluramine using Sharpless Epoxidation Methods
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We describe one synthesis of (S)-fenfluramine and several syntheses of its precursors (R)- and (S)-1-(meta-trifluoromethylphenyl)propan-2-ols.They were obtained from the asymmetric epoxidation of the primary allylic alcohol 5 and from the kinetic resolution with asymmetric epoxidation of teh secondary allylic alcohol 6.
- Goument, Bertrand,Duhamel, Lucette,Mauge, Robert
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p. 171 - 188
(2007/10/02)
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- Epoxides, amino alcohols, and aziridines as key intermediates in the asymmetric synthesis of (S)-fenfluramine
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The epoxides 3E, 3Z and 8 were obtained from the isomeric alkenes 2E, 2Z and 7.The epoxides were ring-opened by ethylamine in ethanol yielding mixtures of the amino alcohols 4E and 11E, 4T and 11T, and 9, respectively, which were transformed into the aziridines 5trans, 5cis and 12.The regiospecific Pd/C-catalyzed reduction of these aziridines gave fenfluramine 1.The three epoxides 3trans, 3cis and 8 were reduced regiospecifically into 1-propan-2-ol 6, a potent precursor to fenfluramine 1.The validity of our method for asymmettric synthesis has been demonstrated by a synthesis of (S)-fenfluramine 1 starting from the amino alcohol (S)-9.Keyword - fenfluramine / asymmetric synthesis / epoxide / amino alcohol / aziridine / regiospecific catalytic hydrogenation / 1-propan-2-ols
- Goument, B.,Duhamel, L.,Mauge, R.
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p. 459 - 466
(2007/10/02)
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