- Light-Enabled Enantiodivergence: Stereospecific Reduction of Activated Alkenes Using a Single Organocatalyst Enantiomer
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Light-enabled enantiodivergence is demonstrated in which the alkene substrate configuration is manipulated (E → Z) prior to organocatalytic reduction with a chiral thiourea and Hantzsch ester. This allows stereodivergent reduction to be regulated at the substrate level with high fidelity and mitigates the need for a second, enantiomeric catalyst (up to 93:07 and 95:5 er). The synthetic utility of this strategy has been demonstrated in the synthesis of the weight-loss drug (R)-Lorcaserin (Belviq) and a potent AMPA modulator.
- Hostmann, Theresa,Molloy, John J.,Bussmann, Kathrin,Gilmour, Ryan
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supporting information
p. 10164 - 10168
(2019/12/24)
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- Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers
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Water enables new catalytic reactions for otherwise unreactive substrate systems. Under the “on water” reaction conditions, extremely unreactive β,β-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers. The developed “on water” protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogs with all-carbon quaternary stereogenic centers at the β-position, which might show highly interesting pharmaceutical properties.
- Sim, Jae Hun,Song, Choong Eui
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p. 1835 - 1839
(2017/02/05)
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- Substrate Scope Evaluation of the Enantioselective Reduction of β-Alkyl-β-arylnitroalkenes by Old Yellow Enzymes 1-3 for Organic Synthesis Applications
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The substrate scope of the old yellow enzyme catalyzed reduction of β-alkyl-β-arylnitroalkenes is investigated. Compounds bearing either alkyl chains of increasing length at the carbon atom in position β to the nitro group or different substituents on the aromatic ring are prepared and submitted to bioreduction, to define the synthetic potential of this enantioselective reaction in the preparation of chiral fine chemicals. The versatility of the resulting nitroalkanes as chiral building blocks is shown by reducing the nitro group into a primary amine and by converting it into a carboxylic acid moiety by Meyer reaction. An "explosion" of chiral products can be observed by combining the highly enantioselective ene-reductase-mediated reduction of nitroalkenes with the chemical versatility of the nitro group.
- Bertolotti, Mattia,Brenna, Elisabetta,Crotti, Michele,Gatti, Francesco G.,Monti, Daniela,Parmeggiani, Fabio,Santangelo, Sara
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p. 577 - 583
(2016/02/23)
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- Synthesis of 3-Benzazepines by Metal-Free Oxidative C–H Bond Functionalization–Ring Expansion Tandem Reaction
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A metal-free synthesis of biologically important benzazepines is achieved through a single synthetic operation involving an oxidative C–H bond functionalization and ring expansion with diazomethanes as key reagent. This represents a new, strong methodology for the straightforward construction of the seven-ring N-heterocyclic structures under mild conditions using a 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxoammonium salt as oxidant. Moderate to good yields are achieved from simple, readily available tetrahydroisoquinolines, and this methodology has been further successfully applied for the synthesis of the 3-benzazepine drug Lorcaserin. A possible mechanistic pathway for the ring expansion step, comprising the extrusion of nitrogen in a concerted asynchronic process, is proposed based on both mechanistic proof and density function theory (DFT) calculations. (Figure presented.).
- Gini, Andrea,Bamberger, Julia,Luis-Barrera, Javier,Zurro, Mercedes,Mas-Ballesté, Rubén,Alemán, José,Manche?o, Olga García
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p. 4049 - 4056
(2016/12/30)
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- Enantioselective iridium-catalyzed hydrogenation of β,β-disubstituted nitroalkenes
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An iridium complex with a newly prepared chiral spiro amino-phosphine ligand efficiently catalyzed the hydrogenation of both β-aryl-β-methyl-nitroalkenes and β-alkyl-β-methyl-nitroalkenes to the corresponding saturated nitroalkanes, which represents the f
- Yu, Yan-Bo,Cheng, Lei,Li, Yi-Pan,Fu, Yue,Zhu, Shou-Fei,Zhou, Qi-Lin
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supporting information
p. 4812 - 4815
(2016/04/09)
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- Iridium-Catalyzed Enantioselective Hydrogenation of β,β-Disubstituted Nitroalkenes
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A highly efficient, iridium-catalyzed, enantioselective hydrogenation of β,β-disubstituted nitroalkenes has been developed. Using a complex consisting of iridium and (S,S)-f-spiroPhos as the catalyst, a variety of β,β-disubstituted nitroalkenes were successfully hydrogenated to the corresponding chiral nitroalkanes with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON=1000).
- Liu, Man,Kong, Duanyang,Li, Meina,Zi, Guofu,Hou, Guohua
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p. 3875 - 3879
(2016/01/25)
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- PREPARATION OF CHIRAL 1-METHYL-2,3,4,5-1H-BENZODIAZEPINES VIA ASYMMETRIC REDUCTION OF ALPHA-SUBSTITUTED STYRENES
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The present invention provides an asymmetric and economic synthesis of 8-chloro-1-methyl-2,3,4,5-tetrahydro-1 H-benzo[d]azepine via novel intermediates applying an asymmetric enzymatic, biomimetic or catalytic reduction. The present invention also provides a novel green asymmetric catalytic reduction adapted for an aqueous medium to be applied in the synthesis of 8-chloro-1-methyl-2,3,4,5-tetrahydro-1 H-benzo[d]azepine or novel intermediates.
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Page/Page column 41; 42
(2015/01/07)
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- Rh-catalyzed highly enantioselective hydrogenation of nitroalkenes under basic conditions
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Go catalytic! A highly enantioselective hydrogenation of β,β-disubstituted nitroalkenes and isomeric mixtures of nitroalkenes by using a Rh/DuanPhos catalytic system under basic conditions has furnished a convenient approach to β-chiral nitroalkanes, whic
- Li, Shengkun,Huang, Kexuan,Zhang, Jiwen,Wu, Wenjun,Zhang, Xumu
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supporting information
p. 10840 - 10844
(2013/09/02)
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- Highly enantioselective hydrogenation of β,β-disubstituted nitroalkenes
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Building the building blocks: A highly enantioselective hydrogenation of ?-aryl-?-alkyl disubstituted nitroalkenes 1 has been developed. This method results in enantiomerically pure nitroalkanes 2, which are versatile precursors for chemical synthesis.
- Li, Shengkun,Huang, Kexuan,Cao, Bonan,Zhang, Jiwen,Wu, Wenjun,Zhang, Xumu
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p. 8573 - 8576
(2012/09/10)
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- Organocatalytic asymmetric transfer hydrogenation of nitroolefins
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We describe a highly efficient and highly enantioselective Hantzsch ester mediated conjugate transfer hydrogenation of β,β-disubstituted nitroolefins that is catalyzed by a Jacobsen-type thiourea catalyst. Copyright
- Martin, Nolwenn J. A.,Ozores, Lidia,List, Benjamin
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p. 8976 - 8977
(2008/02/10)
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