- Highly efficient synthesis of chiral α-CF3 amines via Rh-catalyzed asymmetric hydrogenation
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Highly enantioselective catalytic asymmetric hydrogenation of α-CF3-enamides has been achieved by employing rhodium-DuanPhos as the catalyst, which provides a readily accessible method for the synthesis of chiral trifluoromethylated amines. The reaction has a broad substrate scope; both aryl- and alkyl-substituted α-CF3-enamides worked smoothly and afford the corresponding chiral amines in high yields and excellent enantioselectivities (up to 99% ee).
- Jiang, Jun,Lu, Wenxin,Lv, Hui,Zhang, Xumu
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p. 1154 - 1156
(2015/03/14)
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- Stereoselective transformations of α-trifluoromethylated ketoximes to optically active amines by enzyme-nanometal cocatalysis: Synthesis of (s)-inhibitor of phenylethanolamine n-methyltransferase
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One-pot cascade synthesis of optically active α-trifluoromethylated amines directly from ketoximes was accomplished with the use of Candida antarctica lipase B and catalysts prepared by atomic layer deposition (ALD). Compared to the commercial palladium catalyst, the ALD-prepared catalysts showed much higher activity and afforded various α-trifluoromethylated amides in good yields and with high enantioselectivity. One of the enantiopure amides was further hydrolyzed into the corresponding amine, which was treated as a crucial starting material for total synthesis of (S)-inhibitor of phenylethanolamine N-methyltransferase without loss of chiral information.
- Cheng, Guilin,Wu, Qi,Shang, Zeyu,Liang, Xinhua,Lin, Xianfu
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p. 2129 - 2133
(2014/08/05)
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- Chemoenzymatic dynamic kinetic resolution of α-trifluoromethylated amines: Influence of substitutions on the reversed stereoselectivity
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Enzymatic resolution of α-trifluoromethylated amines via kinetic resolution (KR), dynamic kinetic resolution (DKR) employing CALB-Pd/Al 2O3, and a one-pot sequential process of KR/DKR/KR was investigated comparatively for the first time. Although CALB-catalyzed KR of α-trifluoromethylated amines with substituents of methyl (1a), isopropyl (1c), phenyl (1d) and benzyl group (1e) can provide good stereoselectivity factors E from 31 to >200 respectively, DKR and sequential process of KR/DKR/KR possess better practical application potential because of the higher conversion (62%-84%) and the similar enantiomeric excesses (90%-99%). The enantiopreference and inversion for the α-trifluoromethylated amines displayed by CALB were observed and explained by docking modes. Namely, for 1,1,1-trifluoro-2-propylamine (1a), the product amide with R-configuration was obtained, and the enantiopreference was converted to S for the amines (1b-1e) with substituents larger than methyl group. The catalysts recycle, and scale-up experiments were demonstrated successfully. All these results indicated the high efficiency and green feature of this enzymatic process, and its application significance.
- Cheng, Guilin,Xia, Bo,Wu, Qi,Lin, Xianfu
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p. 9820 - 9828
(2013/09/02)
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- A new strategy for the synthesis of optically pure β-fluoroalkyl β-amino acid derivatives
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(Chemical Equation Presented) The first general approach for the diastereoselective formation of a variety of optically pure anti/β- fluoroalkyl β-amino acid derivatives is described. The process relies on the stereocontrolled reaction, mediated by a remo
- Fustero, Santos,Pozo, Carlos Del,Catalan, Silvia,Aleman, Jose,Parra, Alejandro,Marcos, Vanesa,Ruano, Jose Luis Garcia
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supporting information; experimental part
p. 641 - 644
(2009/08/14)
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