- Markovnikov Wacker-Tsuji Oxidation of Allyl(hetero)arenes and Application in a One-Pot Photo-Metal-Biocatalytic Approach to Enantioenriched Amines and Alcohols
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The Wacker-Tsuji aerobic oxidation of various allyl(hetero)arenes under photocatalytic conditions to form the corresponding methyl ketones is presented. By using a palladium complex [PdCl2(MeCN)2] and the photosensitizer [Acr-Mes]ClO4 in aqueous medium and at room temperature, and by simple irradiation with blue led light, the desired carbonyl compounds were synthesized with high conversions (>80%) and excellent selectivities (>90%). The key process was the transient formation of Pd nanoparticles that can activate oxygen, thus recycling the Pd(II) species necessary in the Wacker oxidative reaction. While light irradiation was strictly mandatory, the addition of the photocatalyst improved the reaction selectivity, due to the formation of the starting allyl(hetero)arene from some of the obtained by-products, thus entering back in the Wacker-Tsuji catalytic cycle. Once optimized, the oxidation reaction was combined in a one-pot two-step sequential protocol with an enzymatic transformation. Depending on the biocatalyst employed, i. e. an amine transaminase or an alcohol dehydrogenase, the corresponding (R)- and (S)-1-arylpropan-2-amines or 1-arylpropan-2-ols, respectively, could be synthesized in most cases with high yields (>70%) and in enantiopure form. Finally, an application of this photo-metal-biocatalytic strategy has been demonstrated in order to get access in a straightforward manner to selegiline, an anti-Parkinson drug. (Figure presented.).
- Albarrán-Velo, Jesús,Gotor-Fernández, Vicente,Lavandera, Iván
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p. 4096 - 4108
(2021/08/19)
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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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- In vitro biocatalytic pathway design: Orthogonal network for the quantitative and stereospecific amination of alcohols
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The direct and efficient conversion of alcohols into amines is a pivotal transformation in chemistry. Here, we present an artificial, oxidation-reduction, biocatalytic network that employs five enzymes (alcohol dehydrogenase, NADP-oxidase, catalase, amine dehydrogenase and formate dehydrogenase) in two concurrent and orthogonal cycles. The NADP-dependent oxidative cycle converts a diverse range of aromatic and aliphatic alcohol substrates to the carbonyl compound intermediates, whereas the NAD-dependent reductive aminating cycle generates the related amine products with >99% enantiomeric excess (R) and up to >99% conversion. The elevated conversions stem from the favorable thermodynamic equilibrium (K′eq = 1.88 × 1042 and 1.48 × 1041 for the amination of primary and secondary alcohols, respectively). This biocatalytic network possesses elevated atom efficiency, since the reaction buffer (ammonium formate) is both the aminating agent and the source of reducing equivalents. Additionally, only dioxygen is needed, whereas water and carbonate are the by-products. For the oxidative step, we have employed three variants of the NADP-dependent alcohol dehydrogenase from Thermoanaerobacter ethanolicus and we have elucidated the origin of the stereoselective properties of these variants with the aid of in silico computational models.
- Knaus, Tanja,Cariati, Luca,Masman, Marcelo F,Mutti, Francesco G.
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supporting information
p. 8313 - 8325
(2017/10/19)
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- Visible-Light-Mediated Anti-Markovnikov Hydration of Olefins
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Considering that stoichiometric borane and oxidant are required in the classical alkene anti-Markovnikov hydration process, it remains appealing to achieve the transformation in a catalytic protocol. Herein, a visible-light-mediated anti-Markovnikov addition of water to alkenes by using an organic photoredox catalyst in conjunction with a redox-active hydrogen atom donor was developed, which avoided the need for a transition-metal catalyst, stoichiometric borane, as well as oxidant. Both terminal and internal olefins are readily accommodated in this transformation to obtain corresponding primary and secondary alcohols in good yields with single regioselectivity. This procedure can be scaled up to gram scale with a 230 turnover number based on photocatalyst.
- Hu, Xia,Zhang, Guoting,Bu, Faxiang,Lei, Aiwen
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p. 1432 - 1437
(2017/08/09)
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- Direct Alkylation of Amines with Primary and Secondary Alcohols through Biocatalytic Hydrogen Borrowing
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The reductive aminase from Aspergillus oryzae (AspRedAm) was combined with a single alcohol dehydrogenase (either metagenomic ADH-150, an ADH from Sphingobium yanoikuyae (SyADH), or a variant of the ADH from Thermoanaerobacter ethanolicus (TeSADH W110A)) in a redox-neutral cascade for the biocatalytic alkylation of amines using primary and secondary alcohols. Aliphatic and aromatic secondary amines were obtained in up to 99 % conversion, as well as chiral amines directly from the racemic alcohol precursors in up to >97 % ee, releasing water as the only byproduct.
- Montgomery, Sarah L.,Mangas-Sanchez, Juan,Thompson, Matthew P.,Aleku, Godwin A.,Dominguez, Beatriz,Turner, Nicholas J.
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supporting information
p. 10491 - 10494
(2017/08/22)
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- Chiral-at-metal iridium complex for efficient enantioselective transfer hydrogenation of ketones
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A bis-cyclometalated iridium(iii) complex with metal-centered chirality catalyzes the enantioselective transfer hydrogenation of ketones with high enantioselectivities at low catalyst loadings down to 0.002 mol%. Importantly, the rate of catalysis and enantioselectivity are markedly improved in the presence of a pyrazole co-ligand. The reaction is proposed to proceed via an iridium-hydride intermediate exploiting metal-ligand cooperativity (bifunctional catalysis).
- Tian, Cheng,Gong, Lei,Meggers, Eric
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supporting information
p. 4207 - 4210
(2016/03/19)
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- Base-Metal-Catalyzed Regiodivergent Alkene Hydrosilylations
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A complementary set of base metal catalysts has been developed for regiodivergent alkene hydrosilylations: iron complexes of phosphine-iminopyridine are selective for anti-Markovnikov hydrosilylations (linear/branched up to >99:1), while the cobalt complexes bearing the same type of ligands provide an unprecedented high level of Markovnikov selectivity (branched/linear up to >99:1). Both systems exhibit high efficiency and wide functional group tolerance. Regiodivergent alkene hydrosilylation has been accomplished with high efficiency using a newly developed set of complementary base metal catalyst systems. An inversion of regioselectivity (linear/branched) from >99:1 to 1:99 is obtained when the iron version of the catalyst is exchanged for a cobalt-containing analogue.
- Du, Xiaoyong,Zhang, Yanlu,Peng, Dongjie,Huang, Zheng
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supporting information
p. 6671 - 6675
(2016/06/08)
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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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experimental part
p. 1985 - 1993
(2012/03/22)
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- Rhizopus arrhizus-mediated asymmetric reduction of arylalkanones: Unusual anti-Prelong products with benzyl alkyl ketones
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Rhizopus arrhizus-mediated microbial reduction of various aryl alkyl ketones afforded chiral carbinols in good yields and high enantiomeric purity. The most striking feature was the formation of the anti-Prelog (R)-alcohols with the benzyl alkyl ketones, while the other ketones ArXCOR (X = (CH 2)n, n = 0 or 2, OCH2 or SCH2 and R = Me/Et/n-Bu) furnished (S)-alcohols.
- Salvi, Neeta A.,Chattopadhyay, Subrata
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experimental part
p. 1512 - 1515
(2011/12/14)
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- Assignment of the absolute configurations of l-Aryl-2-propanols with the use of phosphoroselenoyl chlorides as chiral derivatizing agents
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Phosphoroselenoyl chloride bearing a l,1′-bi-2-naphthyl group was reacted with racemic 2-alkanols to give the corresponding esters. Based on the multiple combination of their NMR spectra, a method for the assignment of the absolute configuration of 1 -aryl-2-propanols was established. The solidstate conformations of the esters were confirmed by X-ray structure analyses.
- Murai, Toshiaki,Tsuji, Hiromi,Imaizumi, Satoko,Maruyama, Toshifumi
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supporting information; experimental part
p. 524 - 526
(2010/09/05)
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- PHARMACEUTICAL INTERMEDIATES AND A PROCESS FOR THE PREPARATION THEREOF
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The invention relates to pure enantiomer and in certain cases new racemic-isopropanol derivatives of the general Formula (I) and a process for the preparation thereof. The partly new and partly known compounds of the general Formula (I) are useful pharmaceutical intermediates. The substituent definition of symbols R1, R2 and R3 are as stated in the patent specification.
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Page/Page column 61-62
(2008/06/13)
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- Kinetic and chemical resolution of different 1-phenyl-2-propanol derivatives
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Seven chiral target molecules containing a hydroxy group have been resolved by both biocatalytic and chemical means. The lipase-catalyzed acylation mainly yielded the acylated derivative of the (R)-alcohols with moderate enantiomeric excess and the enantiopure (S)-alcohols. In the course of the chemical resolution, first the dicarboxylic acid monoesters of the target molecules were synthesized and the resolution of these monoesters was attempted by different homochiral bases. By re-resolution and/or optimization of the reaction time and/or recrystallization, respectively, each molecule was produced in very high enantiomeric purity.
- Kiss, Violetta,Egri, Gabriella,Balint, Jozsef,Ling, Istvan,Barkoczi, Jozsef,Fogassy, Elemer
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p. 2220 - 2234
(2007/10/03)
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- PYRIDINE CARBOXYLIC ACID DERIVATIVES AS GLUCOKINASE MODULATORS
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A compound of Formula (I): wherein: A is phenyl or a 5- or 6-membered heteroaryl ring, optionally substituted; R1 and R2 are selected from hydrogen and methyl; with the proviso that at least one of R1 and R2 is
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Page/Page column 34
(2010/02/11)
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- Highly enantioselective stereo-inverting sec-alkylsulfatase activity of hyperthermophilic Archaea
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rac-sec-Alkyl sulfate esters 1a-8a were resolved in low to excellent enantioselectivities with E-values up to > 200 using whole cells of aerobically-grown hyperthermophilic sulfur-metabolizers, such as Sulfolobus solfataricus DSM 1617, Sulfolobus shibatae DSM 5389 and, most notably, Sulfolobus acidocaldarius DSM 639. Significantly enhanced selectivities were obtained using cells grown on sucrose-enriched Brock-medium. The stereochemical course of this biohydrolysis was shown to proceed with strict inversion of configuration, thus the preferred (R)-enantiomers were converted into the corresponding (S)-sec-alcohols to furnish a homochiral product mixture. The Royal Society of Chemistry 2005.
- Wallner, Sabine R.,Nestl, Bettina M.,Faber, Kurt
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p. 2652 - 2656
(2007/10/03)
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- Palladium-catalyzed reduction of ketones with nBu2SnH2
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Whereas the Pd(PPh3)4-catalyzed reduction of ketones with nBu3SnH does not proceed at all, the use of nBu2SnH2, instead of nBu3SnH, leads to the efficient reduction of a variety of ketones in the presence of a catalytic amount of Pd(PPh3)4 under mild conditions, providing the corresponding alcohols in good yields. The stereoselectivity in the reduction of cyclic ketones is also investigated by using this Pd(PPh3)4/nBu2SnH2 reduction system.
- Kamiya, Ikuyo,Ogawa, Akiya
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p. 1701 - 1703
(2007/10/03)
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