- Stereoselective Synthesis of 1-Arylpropan-2-amines from Allylbenzenes through a Wacker-Tsuji Oxidation-Biotransamination Sequential Process
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Herein, a sequential and selective chemoenzymatic approach is described involving the metal-catalysed Wacker-Tsuji oxidation of allylbenzenes followed by the amine transaminase-catalysed biotransamination of the resulting 1-arylpropan-2-ones. Thus, a series of nine optically active 1-arylpropan-2-amines were obtained with good to very high conversions (74–92%) and excellent selectivities (>99% enantiomeric excess) in aqueous medium. The Wacker-Tsuji reaction has been exhaustively optimised searching for compatible conditions with the biotransamination experiments, using palladium(II) complexes as catalysts and iron(III) salts as terminal oxidants in aqueous media. The compatibility of palladium/iron systems for the chemical oxidation with commercially available and made in house amine transaminases was analysed, finding ideal conditions for the development of a general and stereoselective cascade sequence. Depending on the selectivity displayed by selected amine transaminase, it was possible to produce both 1-arylpropan-2-amines enantiomers under mild reaction conditions, compounds that present therapeutic properties or can be employed as synthetic intermediates of chiral drugs from the amphetamine family. (Figure presented.).
- González-Martínez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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p. 2582 - 2593
(2019/05/15)
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- Direct Reductive Amination of Carbonyl Compounds with H2 Using Heterogeneous Catalysts in Continuous Flow as an Alternative to N-Alkylation with Alkyl Halides
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A general continuous-flow procedure for direct reductive amination of secondary and primary amines with aromatic and aliphatic aldehydes as well as ketones is reported. The use of hydrogen gas and commercially available Pt/C as a heterogeneous catalyst is a key. In addition to exhibiting an excellent functional group tolerance, this method allows the fast formation of C?N bonds without production of any hazardous chemical waste. Applications to the synthesis of key intermediates toward active pharmaceutical ingredients (Donepezil and Arformoterol/Tamsulosin) are also described. (Figure presented.).
- Laroche, Benjamin,Ishitani, Haruro,Kobayashi, Shū
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supporting information
p. 4699 - 4704
(2018/12/04)
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- Reductive amination of ketones with ammonium catalyzed by a newly identified Brevibacterium epidermidis strain for the synthesis of (S)-chiral amines
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The asymmetric reductive amination of achiral ketones with ammonia is a particularly attractive reaction for the synthesis of chiral amines. Although several engineered amine dehydrogenases have been developed by protein engineering for the asymmetric reductive amination of ketones, they all display (R)-stereoselectivity. To date, there is no report of an (S)-stereoselective biocatalyst for this reaction. Herein, a microorganism named Brevibacterium epidermidis ECU1015 that catalyzes the (S)-selective reductive amination of ketones with ammonium has been successfully isolated from soil. Using B. epidermidis ECU1015 as the catalyst, the asymmetric reductive amination of a set of phenylacetone derivatives was successfully carried out, yielding the corresponding (S)-chiral amines with moderate conversion and >99% enantiomeric excess.
- Li, Qing-Hua,Dong, Yuan,Chen, Fei-Fei,Liu, Lei,Li, Chun-Xiu,Xu, Jian-He,Zheng, Gao-Wei
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p. 1625 - 1632
(2018/08/21)
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- Vicinal Diamines as Smart Cosubstrates in the Transaminase-Catalyzed Asymmetric Amination of Ketones
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Transaminases (TAs) have recently been established as catalysts for the asymmetric, reductive amination of prochiral ketones. Depending on the ketone substrate and the amine donor (the cosubstrate), equilibrium constants may limit high conversions; thus, methods to overcome this limitation are required. Removal of the co-product from the reaction equilibrium through spontaneous, intramolecular reactions has provided a successful solution to this problem; therefore, these amine donors have been named “smart cosubstrates”. Here, we present a comparison of various bifunctional amine donors including vicinal diamines as potential structural cosubstrate motifs. Upon TA-catalyzed deamination of 1,2-diamines, spontaneous dimerization of the resulting α-aminoketones and oxidation gave heteroaromatic pyrazines.
- Payer, Stefan E.,Schrittwieser, Joerg H.,Kroutil, Wolfgang
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supporting information
p. 2553 - 2559
(2017/05/12)
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- A stereoselective, catalytic strategy for the in-flow synthesis of advanced precursors of rasagiline and tamsulosin
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The diastereoselective, trichlorosilane-mediate reduction of imines, bearing different and removable chiral auxiliaries, in combination either with achiral bases or catalytic amounts of chiral Lewis bases, was investigated to afford immediate precursors of chiral APIs (Active Pharmaceutical Ingredients). The carbon-nitrogen double bond reduction was successfully performed in batch and in flow mode, in high yields and almost complete stereocontrol. By this metal-free approach, the formal synthesis of rasagiline and tamsulosin was successfully accomplished in micro(meso) flow reactors, under continuous flow conditions. The results of these explorative studies represent a new, important step towards the development of automated processes for the preparation of enantiopure biologically active compounds.
- Brenna, Davide,Pirola, Margherita,Raimondi, Laura,Burke, Anthony J.,Benaglia, Maurizio
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p. 6242 - 6247
(2017/09/30)
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- METHOD FOR PRODUCING NOVEL ORGANOMETALLIC COMPLEX AND AMINE COMPOUND
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The purpose of the invention is to provide a novel organometallic compound that can be utilized as a catalyst having high generality, high activity, and excellent functional group selectivity. The invention pertains to a novel organometallic compound represented by general formula (1) that catalyzes a reductive amination reaction.
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Paragraph 0192
(2016/03/19)
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- Investigation of one-enzyme systems in the ω-transaminase-catalyzed synthesis of chiral amines
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ω-Transaminase (TA) catalyzed asymmetric syntheses of amines were carried out in the one enzyme systems with wild-type enzymes (S)-TA from Pseudomonas aeruginosa, (S)-TA from Paracoccus denitrificans and (R)-TA from Aspergillus terreus. The scope of amine donors and aromatic carbonyl substrates was thoroughly explored. Among the range of potential amino donors, 2-propylamine, 2-butylamine and 1-phenylethylamine were found as promising candidates, which gave superior conversions in the amination reactions compared to other donors. Various prochiral aromatic ketones were accepted as substrates by the investigated enzymes. In most cases, good to excellent conversions (up to 98%) to the amine products with excellent e.e.-values (>99.9% for (S) or (R)) were obtained by the action of a single enzyme and an appropriate amino donor. (S)-TA from Paracoccus denitrificans was found to accept bulky ketones, e.g. 1-indanone, α- and β-tetralone or 2-acetonaphthone, in the asymmetric amination. In some cases the enantiomeric excesses in the amination reactions were dependent on the amino donor. More-over, the influence of the pH, temperature and cosolvents on the outcome of reactions was additionally investigated.
- Fesko, Kateryna,Steiner, Kerstin,Breinbauer, Rolf,Schwab, Helmut,Schuermann, Martin,Strohmeier, Gernot A.
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p. 103 - 110
(2013/10/22)
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- Stereoselectivity of four (R)-selective transaminases for the asymmetric amination of ketones
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Four (R)-ω-transaminases originating from Hyphomonas neptunium (HN-ωTA), Aspergillus terreus (AT-ωTA) and Arthrobacter sp. (ArR-ωTA), as well as an evolved transaminase (ArRmut11-ωTA) were successfully employed for the amination of prochiral ketones leading to optically pure (R)-amines. The first three transaminases displayed perfect stereoselectivity for the amination of all substrates tested (ee >99%). Furthermore, the transaminase AT-ωTA led in most cases to better conversion than ArR-ωTA and HN-ωTA using D-alanine as amine donor. α-Tetralone, which was the only substrate not accepted by HN-ωTA, ArR-ωTA, and AT-ωTA, was successfully transformed with perfect enantioselectivity (ee >99%) into the corresponding optically pure amine employing the variant ArRmut11-ωTA. Copyright
- Mutti, Francesco G.,Fuchs, Christine S.,Pressnitz, Desiree,Sattler, Johann H.,Kroutil, Wolfgang
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experimental part
p. 3227 - 3233
(2012/01/03)
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- Enzymatic enantiomeric resolution of phenylethylamines structurally related to amphetamine
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Both enantiomers of several phenylethylamines, structurally related to amphetamine, have been prepared in good yields and excellent enantiomeric purity by enzymatic kinetic resolution using CAL-B and ethyl methoxyacetate as the acyl donor. In the case of the 4-hydroxyderivative of amphetamine (compound 4i), the S enantiomer racemized possibly in a dynamic kinetic resolution (DKR) under the enzymatic conditions used. The Royal Society of Chemistry 2011.
- Munoz, Lourdes,Rodriguez, Anna M.,Rosell, Gloria,Bosch, M. Pilar,Guerrero, Angel
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p. 8171 - 8177
(2012/01/04)
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- Asymmetric synthesis of optically pure pharmacologically relevant amines employing ω-transaminases
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Various ω-transaminases were tested for the synthesis of enantiomerically pure amines from the corresponding ketones employing D- or L-alanine as amino donor and lactate dehydrogenase to remove the side-product pyruvate to shift the unfavourable reaction equilibrium to the product side. Both enantiomers, (R)- and (S)-amines, could be prepared with up to 99% ee and >99% conversions within 24 h at 50 mM substrate concentration. The activity and stereoselectivity of the amination reaction depended on the ω-transaminase and substrate employed; furthermore the co-solvent significantly influenced both the stereoselectivity and activity of the transaminases. Best results were obtained by employing ATA-117 to obtain the (R)-enantiomer and ATA-113 or ATA-103 to access the (S)-enantiomer with 15% v v-1 DMSO.
- Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Rozzell, David,Kroutil, Wolfgang
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scheme or table
p. 2761 - 2766
(2009/10/06)
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- Formal asymmetric biocatalytic reductive amination
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All for one: A combination of three biocatalysts (ω-transaminase, alanine dehydrogenase, and an enzyme such as formate dehydrogenase for cofactor recycling) catalyze a cascade to achieve the asymmetric transformation of a ketone into a primary α-chiral unprotected amine through a formal stereoselective reductive amination (see scheme). Only ammonia and the reducing agent (formate) are consumed during this reaction. (Chemical Equation Presented).
- Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Guebitz, Georg M.,Rozzell, David,Kroutil, Wolfgang
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supporting information; experimental part
p. 9337 - 9340
(2009/05/15)
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- CAL-B-catalyzed resolution of some pharmacologically interesting β-substituted isopropylamines
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Some pharmacologically active amines such as amphetamine, the isomeric o-, m- and p-methoxyamphetamines, 4-phenylbutan-2-amine and mexiletine, as well as their corresponding acetamides, have been prepared in high yields and with very high enantiomeric excesses. The method consists of the Candida antarctica lipase B (CAL-B)-mediated enantioselective acetylation of racemic amines using ethyl acetate as solvent and acyl donor. The enzyme follows Kazlauskas' rule with all amines, (R)-amides being obtained as the major enantiomer in all cases. From the conversion values measured for both enantiomers, it can be deduced that the size of the substituents attached to the stereocenter is responsible for the enantioselectivity and rate of some of these reactions.
- Gonzalez-Sabin, Javier,Gotor, Vicente,Rebolledo, Francisca
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p. 1315 - 1320
(2007/10/03)
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- An efficient enantioselective synthesis of (R,R)-formoterol, a potent bronchodilator, using lipases
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The potent β2-adrenergic receptor agonist formoterol (R,R)-1 has been obtained in enantiomerically pure form by a convenient chemoenzymatic approach by coupling of epoxide (R)-6 with the unprotected primary amine (R)-9. Both chiral precursors have been prepared by enantiodifferentiation processes involving Pseudomonas cepacia (lipase PS) and Candida antarctica lipase (CALB), respectively. For the resolution of amine 9, we have found that utilization of triethylamine as non-reactive base enhances the reaction rate and the enantioselectivity of the process. The key coupling reaction of (R)-6 and (R)-9 has been conducted through derivatization of the amine with the labile trimethylsilyl group, which liberates the amino group of the resulting amino alcohol (R,R)-11 upon column chromatography purification. In this way, the overall approach is shorter than others previously described. Copyright (C) 2000 Elsevier Science Ltd.
- Campos, Francisco,Bosch, M. Pilar,Guerrero, Angel
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p. 2705 - 2717
(2007/10/03)
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- Asymmetric synthesis of phenylisopropylamines
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The synthesis of enantiomers of a series of methoxy- and alkyl- substituted phenylisopropylamines is described. The synthesis comprises reducing the imines, formed by the reaction of appropriate phenylacetones with either (+)- or (-)-α-methylbenzylamine, by low-pressure reduction techniques, and subsequently subjecting the optically active N-(α-phenethyl)phenylisopropylamine derivative to hydrogenolysis. The hydrogenolysis products are characterized by enantiomeric purities in the range of 96 - 99%. Yields of products are approximately 60%.
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