- Organocatalytic kinetic resolution of N-boc-isoxazolidine-5-ones
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Easily accessible racemic N-Boc-isoxazolidine-5-ones undergo enantioselective alcoholysis promoted by double hydrogen bond donor amine organocatalysts, resulting in their effective kinetic resolution.
- Straub, Matthew R.,Birman, Vladimir B.
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p. 984 - 988
(2021/02/06)
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- Chemical kinetic resolution of unprotected β-substituted β-amino acids using recyclable chiral ligands
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The first chemical method for resolution of N,C-unprotected β-amino acids was developed through enantioselective formation and disassembly of nickel(II) complexes under operationally convenient conditions. The specially designed chiral ligands are inexpensive and can be quantitatively recycled along with isolation of the target β-substituted-β-amino acids in good yields and excellent enantioselectivity. The method features a broad synthetic generality including β-aryl, β-heteroaryl, and β-alkyl-derived β-amino acids. The procedure is easily scaled up, and was used for the synthetically and economically advanced preparation of the anti-diabetic drug sitagliptin. The nick of time: A chemical method for resolution of unprotected β-amino acids rac-1 was developed through enantioselective formation and disassembly of nickel(II) complexes to deliver the target β-substituted β-amino acids in good yields and excellent enantioselectivity. The chiral ligands are inexpensive and can be quantitatively recycled. The procedure was used for the preparation of anti-diabetic drug sitagliptin.
- Zhou, Shengbin,Wang, Jiang,Chen, Xia,Acena, Jose Luis,Soloshonok, Vadim A.,Liu, Hong
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supporting information
p. 7883 - 7886
(2014/08/05)
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- Tataricins A and B, two novel cyclotetrapeptides from Aster tataricus, and their absolute configuration assignment
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Two novel cyclotetrapeptides, tataricins A and B, with a unique cyclopeptide backbone and aδ 2,4Pro side chain, were isolated from the traditional Chinese medicine Aster tataricus. Their structures and absolute configurations were determined using a combination of spectroscopic data, the advanced Marfey's method, and a total synthesis. Copyright
- Xu, Hui-Min,Yi, Hua,Zhou, Wen-Bing,He, Wen-Jun,Zeng, Gang-Zhi,Xu, Wen-Yan,Tan, Ning-Hua
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supporting information
p. 1380 - 1383
(2013/04/23)
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- Asymmetric biocatalysis of S-3-amino-3-phenylpropionic acid with new isolated Methylobacterium Y1-6
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β-amino acids are widely used in drug research, and S-3-amino-3-phenylpropionic acid (S-APA) is an important pharmaceutical intermediate of S-dapoxetine, which has been approved for the treatment of premature ejaculation. Chiral catalysis is an excellent method for the preparation of enantiopure compounds. In this study, we used (±)-ethyl-3-amino-3-phenylpropanoate (EAP) as the sole carbon source. Three hundred thirty one microorganisms were isolated from 30 soil samples, and 17 strains could produce S-APA. After three rounds of cultivation and identification, the strain Y1-6 exhibiting the highest enantioselective activity of S-APA was identified as Methylobacterium oryzae. The optimal medium composition contained methanol (2.5 g/L), 1,2-propanediol (7.5 g/L), soluble starch (2.5 g/L), and peptone (10 g/L); it was shaken at 220 rpm for 4-5 days at 30 C. The optimum condition for biotransformation of EAP involved cultivation at 37 C for 48 h with 120 mg of wet cells and 0.64 mg of EAP in 1 ml of transfer solution. Under this condition, substrate ee was 92.1% and yield was 48.6%. We then attempted to use Methylobacterium Y1-6 to catalyze the hydrolytic reaction with substrates containing 3-amino-3-phenyl-propanoate ester, N-substituted-β-ethyl-3-amino-3-phenyl-propanoate, and γ-lactam. It was found that 5 compounds with ester bonds could be stereoselectively hydrolyzed to S-acid, and 2 compounds with γ-lactam bonds could be stereoselectively hydrolyzed to (-)-γ-lactam.
- Li, Yi,Wang, Wenfu,Huang, Yumian,Zou, Qianwen,Zheng, Guojun
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p. 1674 - 1678
(2013/11/19)
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- Novel thiazolones as HCV NS5B polymerase allosteric inhibitors: Further designs, SAR, and X-ray complex structure
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Structure-activity relationships (SAR) of 1 against HCV NS5B polymerase were described. SAR explorations and further structure-based design led to the identifications of 2 and 3 as novel HCV NS5B inhibitors. X-ray structure of 3 in complex with NS5B polymerase was obtained at a resolution of 2.2 A, and confirmed the design.
- Yan, Shunqi,Larson, Gary,Wu, Jim Z.,Appleby, Todd,Ding, Yili,Hamatake, Robert,Hong, Zhi,Yao, Nanhua
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- The Mannich reaction of malonates with simple imines catalyzed by bifunctional cinchona alkaloids: Enantioselective synthesis of β-amino acids
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We describe the first efficient, direct asymmetric Mannich reactions with malonates and N-Boc aryl and alkyl imines by cooperative hydrogen-bonding catalysis with a cinchona alkaloid bearing a thiourea functionality. We have also extended the scope of thi
- Song, Jun,Wang, Yi,Deng, Li
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p. 6048 - 6049
(2007/10/03)
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- Synthesis and binding activity of endomorphin-1 analogues β-amino acids
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Endomorphin-1 (Tyr-Pro-Trp-PheNH2) has been proposed as the most potent endogenous ligand of the μ-opioid receptors. In this paper, we describe the synthesis of some endomorphin-1 based tetrapeptides in which a residue of the sequence Tyr-Pro-Trp-PheNH2 is replaced by the corresponding β-isomer. These novel peptides showed different affinities for the opioid receptors labeled with [3H]-DAMGO in rat brain membranes, depending on the β-amino acid. In particular, the tetrapeptide containing β-Pro (Tyr-β-(R)-Pro-Trp-PheNH2) displayed a higher affinity than endogenous endomorphin-1, as revealed by their K(i) values (0.33 and 11.1 nM, respectively). (C) 2000 Elsevier Science Ltd.
- Cardillo, Giuliana,Gentilucci, Luca,Melchiorre, Paolo,Spampinato, Santi
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p. 2755 - 2758
(2007/10/03)
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- α-Oxymethyl ketone enolates for the asymmetric Mannich reaction. From acetylene and N-alkoxycarbonylimines to β-amino acids
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The insufficient diastereoselectivity and generality, which are the main problems of the 'acetate' aza - aldol reaction, can now be addressed through the reaction of the lithium enolate of endo-O-trimethylsilyl acetyl isoborneol with various N[(p-tolylsul
- Palomo, Claudio,Oiarbide, Mikel,Gonzalez-Rego, M. Concepcion,Sharma, Arun K.,Garcia, Jesus M.,Gonzalez, Alberto,Landa, Cristina,Linden, Anthony
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p. 1063 - 1066
(2007/10/03)
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