- Asymmetric Catalytic Meerwein-Ponndorf-Verley Reduction of Ketones with Aluminum(III)-VANOL Catalysts
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We report herein an efficient aluminum-catalyzed asymmetric MPV reduction of ketones with broad substrate scope and excellent yields and enantiomeric inductions. A variety of aromatic (both electron-poor and electron-rich) and aliphatic ketones were converted to chiral alcohols in good yields with high enantioselectivities (26 examples, 70-98percent yield and 82-99percent ee). This method operates under mild conditions (-10 °C) and low catalyst loading (1-5 mol percent). Furthermore, this process is catalyzed by the earth-abundant main-group element aluminum and employs 2-propanol as the hydride source.
- Guan, Yong,Mohammadlou, Aliakbar,Staples, Richard,Sullivan, Ryan P.,Wulff, William D.,Yin, Xiaopeng,Zheng, Li
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p. 7188 - 7194
(2020/07/21)
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- Lipase mediated enzymatic kinetic resolution of phenylethyl halohydrins acetates: A case of study and rationalization
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Racemic phenylethyl halohydrins acetates containing several groups attached to the aromatic ring were resolved via hydrolysis reaction in the presence of lipase B from Candida antarctica (Novozym 435). In all cases, the kinetic resolution was highly selective (E > 200) leading to the corresponding (S)-β-halohydrin with ee > 99 %. However, the time required for an ideal 50 % conversion ranged from 15 min for 2,4-dichlorophenyl chlorohydrin acetate to 216 h for 2-chlorophenyl bromohydrin acetate. Six chlorohydrins and five bromohydrins were evaluated, the latter being less reactive. For the β-brominated substrates, steric hindrance on the aromatic ring played a crucial role, which was not observed for the β-chlorinated derivatives. To shed light on the different reaction rates, docking studies were carried out with all the substrates using MD simulations. The computational data obtained for the β-brominated substrates, based on the parameters analysed such as NAC (near attack conformation), distance between Ser-O and carbonyl-C and oxyanion site stabilization were in agreement with the experimental results. On the other hand, the data obtained for β-chlorinated substrates suggested that physical aspects such as high hydrophobicity or induced change in the conformation of the enzymatic active site are more relevant aspects when compared to steric hindrance effects.
- Fonseca, Thiago de Sousa,Vega, Kimberly Benedetti,da Silva, Marcos Reinaldo,de Oliveira, Maria da Concei??o Ferreira,de Lemos, Telma Leda Gomes,Contente, Martina Letizia,Molinari, Francesco,Cespugli, Marco,Fortuna, Sara,Gardossi, Lucia,de Mattos, Marcos Carlos
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- Microbiological bio-reduction of prochiral carbonyl compounds by antimycotic agent Boni Protect
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The selective properties of the fungus Aureobasidium pullulans, in the antifungal agent Boni Protect, were investigated in the fermentative bioreduction of selected carbonyl compounds. Catalyzed by oxidoreductases contained in the microorganism Aureobasidium pullulans highly enantioselective biotransformation of prochiral ketones provides the secondary alcohols when the reaction is done in the presence of specific additives. Aureobasidium pullulans has also proved to be an effective bioreagent in the reduction of α- and β-keto esters. Optically pure hydroxy esters were obtained under fermentation conditions without the use of additives.
- Ko?odziejska, Renata,Studzińska, Renata,Kwit, Marcin,Jelecki, Maciej,Tafelska-Kaczmarek, Agnieszka
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- Synthesis of enantiopure 1,2-azido and 1,2-amino alcohols via regio- and stereoselective ring-opening of enantiopure epoxides by sodium azide in hot water
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A practical and convenient method for the efficient and regio- and stereoselective ring-opening of enantiopure monosubstituted epoxides by sodium azide under hydrolytic conditions is reported. The ring-opening of enantiopure styryl and pyridyl (S)-epoxides by N3- in hot water takes place preferentially at the internal position with complete inversion of configuration to produce (R)-2-azido ethanols with up to 99% enantio- and regioselectivity, while the (S)-adamantyl oxirane provides mainly the (S)-1-adamantyl-2-azido ethanol in excellent yield. In general, 1,2-amino ethanols were obtained in high yield and excellent enantiopurity by the reduction of the chiral 1,2-azido ethanols with PPh3 in water/THF, and then converted into the Boc or acetamide derivatives.
- Wang, Hai-Yang,Huang, Kun,De Jesús, Melvin,Espinosa, Sandraliz,Pi?ero-Santiago, Luis E.,Barnes, Charles L.,Ortiz-Marciales, Margarita
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- An imidazolium-modified chiral rhodium/diamine-functionalized periodic mesoporous organosilica for asymmetric transfer hydrogenation of α-haloketones and benzils in aqueous medium
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The use of a hydrophobic, imidazolium-functionalized periodic mesoporous organosilica for immobilization of chiral organometallic complexes as a heterogeneous catalyst is highly desirable as this catalyst can greatly promote an aqueous organic transformation due to its hydrophobic function and phase-transfer feature in an aqueous medium. Herein, by utilizing a three-component co-condensation strategy, we conveniently incorporate 1,2-bis(triethoxysilyl)ethane, (R,R)-4-((trimethoxysilyl)ethyl)phenylsulfonyl-1,2-diphenylethylene-diamine and 1,3-bis(3-(triethoxysilyl)propyl)-1H-imidazol-3-ium iodide within its silicate network, which is coordinated with (Cp?RhCl2)2, leading to an imidazolium-modified chiral rhodium/diamine-functionalized periodic mesoporous organosilica. A solid-state carbon spectrum discloses its well-defined chiral rhodium/diamine active species, and its X-ray diffraction; nitrogen adsorption-desorption measurement and transmission electron microscopy images reveal its ordered dimensional-hexagonal mesostructure. As a bifunctional heterogeneous catalyst, this periodic mesoporous organosilica significantly boosts asymmetric transfer hydrogenation of α-haloketones and benzils in water, where the hydrophobic periodic mesoporous organosilica, phase-transfer-featured imidazolium-functionality, and the confined chiral organorhodium catalytic nature are responsible for its catalytic performance. Furthermore, the catalyst can be recovered and recycled seven times without the loss of its catalytic activity, making it an attractive heterogeneous catalyst for asymmetric transfer hydrogenation in an environmentally friendly manner.
- Zhou, Feng,Hu, Xiaoying,Gao, Ming,Cheng, Tanyu,Liu, Guohua
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p. 5651 - 5657
(2016/10/21)
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- Synthesis of optically active α-bromohydrins via reduction of α-bromoacetophenone analogues catalyzed by an isolated carbonyl reductase
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Enantiomerically pure (S)-α-bromohydrins were prepared by the reduction of α-bromoacetophenone analogues catalyzed by an isolated carbonyl reductase from Candida magnolia with high yield and excellent enantiomeric excess when methyl tert-butyl ether was employed as the co-solvent, while avoiding the formation of by-products. This provides a new approach to access these chiral α-bromohydrins which are of pharmaceutical importance.
- Ren, Jie,Dong, Wenyue,Yu, Benqing,Wu, Qiaqing,Zhu, Dunming
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experimental part
p. 497 - 500
(2012/07/28)
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- Chiral epoxides via borane reduction of 2-haloketones catalyzed by spiroborate ester: Application to the synthesis of optically pure 1,2-hydroxy ethers and 1,2-azido alcohols
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An enantioselective borane-mediated reduction of a variety of 2-haloketones with 10% spiroaminoborate ester 1 as catalyst is described. By a simple basic workup of 2-halohydrins, optically active epoxides are obtained in high yield and with excellent enantiopurity (up to 99% ee). Ring-opening of oxiranes with phenoxides or sodium azide is investigated under different reaction conditions affording nonracemic 1,2-hydroxy ethers and 1,2-azido alcohols with excellent enantioselectivity (99% ee) and in good to high chemical yield. 2011 American Chemical Society.
- Huang, Kun,Wang, Haiyang,Stepanenko, Viatcheslav,De Jesus, Melvin,Torruellas, Carilyn,Correa, Wildeliz,Ortiz-Marciales, Margarita
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supporting information; experimental part
p. 1883 - 1886
(2011/06/20)
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- Asymmetric synthesis of β-adrenergic blockers through multistep one-pot transformations involving in situ chiral organocatalyst formation
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Two birds one stone: A new atom-economical one-pot approach to enantioselective chiral drug synthesis, involving in situ multistep organocatalyst formation and the application of the reaction for multistep sequential synthesis of β-adrenergic blockers is disclosed (see scheme).
- Wei, Shengwei,Messerer, Regina,Tsogoeva, Svetlana B.
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supporting information; scheme or table
p. 14380 - 14384
(2012/02/01)
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- The Ru-catalyzed enantioselective preparation of chiral halohydrins and their application in the synthesis of (R)-clorprenaline and (S)-sotalol
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The asymmetric transfer hydrogenation of a series of halo-substituted aryl methyl ketones, including those substituted in both α-methyl and aryl rings, was studied for the preparation of chiral halohydrins. Up to 99.7% ee was obtained with 2-chloro-1-(2-chlorophenyl)ethanone as the substrate and Ru-CsDPEN as the catalyst in an HCOONa/H2O system. (R)-Clorprenaline, a drug used in the treatment of respiratory disorders, such as bronchitis and asthma, and (S)-sotalol, a class-III antiarrhythmic compound, were prepared with these chiral halohydrins.
- Lu, Chuanjun,Luo, Zonghua,Huang, Ling,Li, Xingshu
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experimental part
p. 722 - 727
(2011/08/06)
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- A novel C3-symmetric prolinol-squaramide catalyst for the asymmetric reduction of ketones by borane
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A novel C3-symmetric prolinol-squaramide has been developed for the asymmetric reduction of ketones by borane. By using only 5 mol % catalyst 1a for the reaction, high yields and excellent enantioselectivities (up to 95% yield, 93% ee) were obtained. Moreover, 1a can be easily recovered by simple precipitation and re-used for four cycles without losing the selectivity. Copyright
- Wu, Xiang-Fei,Min, Chang,Nyamzundui, Enkhtsetseg,Zhou, Hai-Bing,Dong, Chune
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experimental part
p. 1640 - 1643
(2011/12/22)
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- Chemo- And stereodivergent preparation of terminal epoxides and bromohydrins through One-Pot biocatalysed reactions: Access to enantiopure Five- and Six-Membered N-Heterocycles
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Different enantiopure terminal epoxides or bromohydrins have chemoselectively been synthesised in one-pot starting from the corresponding a-bromo ketones through alcohol dehydrogenase (ADH)-catalysed processes adding an organic cosolvent and tuning appropriately the medium pH and the temperature. Thus, at neutral pH enantiopure bromohydrins were obtained while using basic conditions (pH 9.5-10) epoxides were isolated as the main product. Furthermore, by simple selection of the biocatalyst, chemo- and stereodivergent transformations were achieved to obtain, e.g., enantiopure prolinol or piperidin-3-ol.
- Bisogno, Fabricio R.,Cuetos, Anibal,Orden, Alejandro A.,Kurina-Sanz, Marcela,Lavandera, Ivan,Gotor, Vicente
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supporting information; experimental part
p. 1657 - 1661
(2010/09/18)
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- (5S)-1-Aza-2-imino-3-oxa-4,4-diphenylbicyclo(3.3.0)octane: a novel chiral catalytic source containing the N-(C{double bond, long}NH)-O moiety for the borane-mediated asymmetric reduction of prochiral ketones
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(5S)-1-Aza-2-imino-3-oxa-4,4-diphenylbicyclo(3.3.0)octane, a novel chiral catalytic source containing the N-(C{double bond, long}NH)-O moiety, has been synthesized and successfully utilized, for the first time, as a chiral catalytic source in the borane-mediated asymmetric reduction of prochiral ketones in refluxing toluene, to provide the corresponding secondary alcohols with up to 93% enantiomeric excess.
- Basavaiah, Deevi,Venkateswara Rao, Kalapala,Sekhara Reddy, Bhavanam
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p. 963 - 967
(2008/02/03)
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- (5S)-1,3-Diaza-2-imino-3-phenylbicyclo[3.3.0]octane: first example of guanidine based in situ recyclable chiral catalytic source for borane-mediated asymmetric reduction of prochiral ketones
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(5S)-1,3-Diaza-2-imino-3-phenylbicyclo[3.3.0]octane has been synthesized and successfully employed, for the first time, as a chiral catalytic source for the borane-mediated asymmetric reduction of prochiral α-halo ketones to provide the corresponding secondary alcohols in high enantiomeric purity. The potential of this guanidine as an in situ recyclable chiral catalytic source for the borane-mediated chiral reduction processes has also been demonstrated.
- Basavaiah, Deevi,Venkateswara Rao, Kalapala,Sekhara Reddy, Bhavanam
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p. 1036 - 1040
(2007/10/03)
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- (2S)-2-Anilinomethylpyrrolidine: an efficient in situ recyclable chiral catalytic source for the borane-mediated asymmetric reduction of prochiral ketones in refluxing toluene
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(2S)-2-Anilinomethylpyrrolidine was successfully utilized as a chiral catalytic source in the borane-mediated asymmetric reduction of prochiral ketones in refluxing toluene to provide the corresponding secondary alcohols with enantiomeric excesses up to 91%. The potential of (2S)-2-anilinomethylpyrrolidine as an in situ recyclable chiral catalytic source in the borane-mediated chiral reduction processes has also been demonstrated.
- Basavaiah, Deevi,Rao, Kalapala Venkateswara,Reddy, Bhavanam Sekhara
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p. 1041 - 1044
(2007/10/03)
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- Synthesis of β-adrenergic blockers (R)-(-)-nifenalol and (S)-(+)-sotalol via a highly efficient resolution of a bromohydrin precursor
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(R)- and (S)-2-bromo-1-(4-nitrophenyl)ethanol are precursors of important β-adrenergic receptor blocking drugs (R)-nifenalol and (S)-sotalol, respectively. Both were obtained in enantiomeric pure forms via a single highly efficient enzymatic transesterification reaction of (±)-2-bromo-1-(4- nitrophenyl)ethanol using immobilized lipase PS-C-II (E >1000; concn 200 g/L), while PS lipase completely failed to react. On the other hand, the hydrolytic method also produced enantiorich precursors though relatively less efficient (PS-C-II, E = 5.1). Out of all the approaches employed the transesterification method proved to be the most efficient.
- Kapoor, Munish,Anand, Naveen,Ahmad, Khursheed,Koul, Surrinder,Chimni, Swapandeep S.,Taneja, Subhash C.,Qazi, Ghulam N.
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p. 717 - 725
(2007/10/03)
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- Asymmetric transfer hydrogenation of ketones catalyzed by hydrophobic metal-amido complexes in aqueous micelles and vesicles
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Asymmetric transfer hydrogenation of ketones, especially α-bromomethyl aromatic ketones, catalyzed by unmodified, hydrophobic transition metal-amido complexes (TsDPEN-M), was performed successfully with significant enhancement of activity, chemoselectivity, and enantio-selectivity (up to 99% ee) in aqueous media containing micelles and vesicles. The hydrophobic catalyst, embedded in micelles constructed from the surfactant cetyltrimethylammonium bromide (CTAB), could be separated from the organic phase along with the products and was recycled for at least six times.
- Wang, Fei,Liu, Hui,Cun, Linfeng,Zhu, Jin,Deng, Jingen,Jiang, Yaozhong
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p. 9424 - 9429
(2007/10/03)
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- A new chiral catalytic source with an N-P=O structural framework containing a proximal hydroxyl group for the borane-mediated asymmetric reduction of prochiral ketones
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(5S)-2-[(1R,2R,3S,5R)-2-Hydroxy-2,6,6-trimethylbicyclo[3.1.1] heptan-3-yloxy]-1,3-diaza-2-phospha-2-oxo-3-phenylbicyclo[3.3.0]octane has been successfully employed as a novel chiral catalytic source (4mol%) for borane-mediated asymmetric reduction of prochiral ketones thus providing the resulting secondary alcohols with up to 96% enantiomeric excess.
- Basavaiah, Deevi,Reddy, Gone Jayapal,Chandrashekar, Vanampally
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- Toward effective chiral catalysts containing the N-P=O structural framework for the borane-mediated asymmetric reduction of prochiral ketones
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Representative chiral catalysts containing the N-P=O structural framework having (5S)-1,3-diaza-2-phospha-2-oxo-3-phenylbicyclo[3.3.0]octane moiety with amino groups of varying steric requirements on phosphorus, have been synthesized and their applications in the borane-mediated asymmetric reduction of prochiral ketones described.
- Basavaiah, Deevi,Reddy, Gone Jayapal,Rao, Kalapala Venkateswara
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p. 1881 - 1888
(2007/10/03)
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- Exploration of the biocatalytic potential of a halohydrin dehalogenase using chromogenic substrates
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Halohydrin dehalogenases are bacterial enzymes that catalyse the reversible formation of epoxides from vicinal halohydrins. A spectrophotometric assay for halohydrin dehalogenases based on the absorption difference between the halohydrin para-nitro-2-bromo-1-phenylethanol and the epoxide para-nitrostyrene oxide was developed. The enantioselectivity of ring-closure reactions catalysed by three different halohydrin dehalogenases could be estimated from the shape of progress curves. Evaluation of ring-opening reactions catalysed by halohydrin dehalogenase from Agrobacterium radiobacter AD1 established that, in addition to Cl- and Br-, nucleophiles such as N3-, CN- and NO2- are also accepted for the ring opening of para-nitrostyrene oxide. The ring-opening reactions with these nucleophiles resulted in highly enantioselective kinetic resolutions, which expands the scope of synthetically valuable conversions catalysed by a halohydrin dehalogenase.
- Lutje Spelberg, Jeffrey H.,Tang, Lixia,Van Gelder, Marc,Kellogg, Richard M.,Janssen, Dick B.
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p. 1083 - 1089
(2007/10/03)
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- (2S,5S)-1,3-Diaza-2-phospha-2-oxo-2-chloro-3-phenylbicyclo[3.3.0]octane: A novel chiral source for borane-mediated catalytic chiral reductions
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(2S,5S)-1,3-Diaza-2-phospha-2-oxo-2-chloro-3-phenylbicyclo[3.3.0]octane has been successfully employed as a chiral catalytic source for the borane mediated asymmetric reductions of prochiral α-halo ketones to provide the desired (S)-secondary alcohols in 81-91% enantiomeric purities, thus for the first time demonstrating the potential of the N-P(=O)Cl structural framework to generate a recoverable, reusable and air stable catalyst for the asymmetric reduction processes.
- Basavaiah, Deevi,Jayapal Reddy, Gone,Chandrashekar, Vanampally
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p. 1125 - 1128
(2007/10/03)
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- cis-1-Amino-2-indanol in asymmetric synthesis. Part I. A practical catalyst system for the enantioselective borane reduction of aromatic ketones
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A new class of oxazaborolidine catalysts has been prepared from optically pure cis-1-amino-2 indanols which are available in large quantities. The asymmetric borane reduction of aromatic ketones using these catalysts has been studied.
- Hong, Yaping,Gao, Yun,Nie, Xiaoyi,Zepp, Charles M.
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p. 6631 - 6634
(2007/10/02)
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