- Easy kinetic resolution of some β-amino alcohols by Candida antarctica lipase B catalyzed hydrolysis in organic media
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Herein, we present an easy and eco-friendly pathway to obtain some enantiomerically enriched β-amino alcohols using essentially as β-blockers. The enzymatic hydrolysis is conducted in hydrophobic organic media, assisted by sodium carbonate and CAL-B. We describe a new and effective procedure in terms of the chemo- and enantioselectivity, which allows for the formation of both enantiomers: the 2-acetamido-1-arylacetates and 2-acetamido-1-arylethanols were obtained with high ee values (up to >99%), while the selectivities reached E >200. The obtained results show a high CAL-B affinity toward the deacylation of the 2-acetamido-1-arylacetates compared to the acylation one. The structure of the 2-acetamido-1-arylacetates had a significant influence on both reactivity and selectivity of the CAL-B catalyzed deacylation. A multigram scale O-deacylation of racemic 2-acetamido-1-phenylacetate has been carried out, giving access both enantiomers with high enantiomeric purity and good isolated chemical yields.
- Alalla, Affef,Merabet-Khelassi, Mounia,Riant, Olivier,Aribi-Zouioueche, Louisa
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p. 1253 - 1259
(2016/11/23)
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- Backbone modification of β-hairpin-forming tetrapeptides in asymmetric acyl transfer reactions
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Synthetic oligopeptides as mimics of enzymes have been increasingly exploited as catalysts for asymmetric reactions, but highly effective oligopeptide catalysts with relatively low molecular weight are still in great demand. In this paper, we showed the conformational engineering of the β-hairpin-forming tetrapeptide 4 which was first reported by Miller's group as the catalyst for the asymmetric acyl transfer reaction of trans-2-(N-acetylamino)cyclohexan-1-ol (krel = 28). Through our backbone modification strategy, thioamide and sulfonamide as the isosteres of amide were introduced in the β-hairpin secondary structure. The thioxo peptides also adopt β-hairpin conformations as the oxopeptide supported by the combined use of NMR, IR, and X-ray techniques. Thioxo tetrapeptide 14 formed a more constrained β-hairpin conformation and therefore delivered much higher enantioselectivity (krel = 109) in the same reaction. Moreover, the examination of the conformational changes of tetrapeptide 8 upon the protonation of the Nπ-methylhistidine moiety provided evidence to explain the variation of its catalytic efficiency in the asymmetric acyl-transfer reaction.
- Chen, Peng,Qu, Jin
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experimental part
p. 2994 - 3004
(2011/07/08)
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- Enantiomers of Ring-Substituted 2-Amino-1-phenylethanols by Pseudomonas cepacia Lipase
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The enantiomers of 2-amino-1-phenylethanols were obtained enantiomerically pure (ee > 95percent) at 50percent conversion by the Pseudomonas cepacia lipase-catalysed O-acylation of amino alcohols or O-deacylation of the corresponding N,O-diacylated compoun
- Lundell, Katri,Kanerva, Liisa T.
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p. 2281 - 2286
(2007/10/03)
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- Baker's Yeast Reduction of α-(Acylamino)acetophenones and Lipase Catalyzed Resolution of 2-Acylamino-1-arylethanols
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Enzymatic reduction of α-acylaminoacetophenones with fermenting baker's yeast afforded optically active (R)-2-acylamino-1-arylethanols.Furthermore, lipase-catalyzed resolution of the 2-acylamino-1-arylethanols using vinyl acetate as an acyl donor resulted in the formation of (S)-1-acetoxy-2-acylamino-1-arylethanols and (R)-2-acylamino-1-arylethanols.
- Izumi, Taeko,Fukaya, Katsumi
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p. 1216 - 1221
(2007/10/02)
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