- Expanding dynamic kinetic protocols: Transaminase-catalyzed synthesis of α-substituted β-amino ester derivatives
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Several α-alkylated β-amino esters have been obtained via DKR processes employing a kit of transaminases and isopropylamine as an amino donor in aqueous medium under mild conditions. Thus, while acyclic α-alkyl-β-keto esters afforded excellent conversions and enantioselectivities, although usually low diastereoselectivities, using more constrained cyclic β-keto esters high to excellent inductions were obtained.
- Cuetos, Anibal,Lavandera, Ivan,Gotor, Vicente
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supporting information
p. 10688 - 10690
(2013/11/06)
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- Efficient synthesis of (1R,2S) and (1S,2R)-2-aminocyclopentanecarboxylic acid ethyl ester derivatives in enantiomerically pure form
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A 4-step synthesis of an optically active synthetic intermediate [(1R,2S)-2-(4′-fluorobenzylamino)cyclopentanecarboxylic acid ethyl ester complex with (S)-(+)-mandelic acid; compound 12, >99% de] required for the preparation of a promising HCV NS5B polymerase inhibitor is reported. This process utilizes mandelic acid as a resolving agent, which can be recovered in good yield by a simple extraction. An optimized version of the chemistry described avoids the use of chromatographic purifications making it suitable for large-scale applications. In addition, the straightforward conversion of compound 12 to enantiomerically pure (1R,2S)-2-aminocyclopentanecarboxylic acid ethyl ester and the corresponding Boc and Cbz derivatives is reported. The preparation of the enantiomer of 12 (compound 15) in enantiomerically pure form and the conversion of this entity to (1S,2R)-2-aminocyclopentanecarboxylic acid ethyl ester and the corresponding Boc and Cbz derivatives is also described.
- Dragovich, Peter S.,Murphy, Douglas E.,Dao, Kimkim,Kim, Sun Hee,Li, Lian-Sheng,Ruebsam, Frank,Sun, Zhongxiang,Tran, Chinh V.,Xiang, Alan X.,Zhou, Yuefen
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experimental part
p. 2796 - 2803
(2009/06/28)
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- The first direct enzymatic hydrolysis of alicyclic β-amino esters: A route to enantiopure cis and trans β-amino acids
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The first direct enzymatic method is reported for the synthesis of cis and trans βamino acid enantiomers through the lipase-catalyzed enantioselective hydrolysis of alicyclic β esters in organic media. High enantioselectivities (E usually > 001) were observed when the Candida antarctica lipase B catalyzed reactions were performed with H2O (0.5 equivalents) in iP iPr2O at 5°C. The resolved products, obtained in good yields (≥42%), could be easily separated.
- Forro, Eniko,Fueloep, Ferenc
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p. 6397 - 6401
(2008/02/13)
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