- Organocatalytic Enantioselective Addition of α-Aminoalkyl Radicals to Isoquinolines
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With a dual organocatalytic system involving a chiral phosphoric acid and a dicyanopyrazine-derived chromophore (DPZ) photosensitizer and under the irradiation with visible light, an enantioselective Minisci-type addition of α-amino acid-derived redox-active esters (RAEs) to isoquinolines has been developed. A variety of prochiral α-aminoalkyl radicals generated from RAEs were successfully introduced on isoquinolines, providing a range of valuable α-isoquinoline-substituted chiral secondary amines in high yields with good to excellent enantioselectivities.
- Liu, Xiangyuan,Liu, Yang,Chai, Guobi,Qiao, Baokun,Zhao, Xiaowei,Jiang, Zhiyong
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supporting information
p. 6298 - 6301
(2018/10/09)
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- Immunomodulatory peptides
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The invention relates to peptides derivatized with a hydrophilic polymer which, in some embodiments, bind to human FcRn and inhibit binding of the Fc portion of an IgG to an FcRn, thereby modulating serum IgG levels. The disclosed compositions and methods may be used in some embodiments, for example, in treating autoimmune diseases and inflammatory disorders. The invention also relates, in further embodiments, to methods of using and methods of making the peptides of the invention.
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- Enhanced conversion of racemic α-arylalanines to (R)-β- arylalanines by coupled racemase/aminomutase catalysis
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(Graph Presented) The Taxus phenylalanine aminomutase (PAM) enzyme converts several (S)-α-arylalanines to their corresponding (R)-β- arylalanines. After incubating various racemic substrateswith 100 μg of PAM for 20 h at 31°C, each (S)-α-arylalanine was enantioselectively isomerized to its corresponding (R)-β-product. With racemic starting materials, the ratio of (R)-β-arylalanine product to the (S)-α-substrate ranged between 0.4 and 1.8, and the remaining nonproductive (R)-α-arylalanine became enriched. To utilize the (R)-α-isomer, the catalysis of a promiscuous alanine racemase from Pseudomonas putida (KT2440) was coupled with that of PAM to increase the production of enantiopure (R)-β-arylalanines from racemic α-arylalanine substrates. The inclusion of a biocatalytic racemization along with the PAM-catalyzed reactionmoderately increased the overall reaction yield of enantiopure β-arylalanines between 4% and 19% (depending on the arylalanine), which corresponded to as much as a 63% increase compared to the turnover with the aminomutase reaction alone. The use of these biocatalysts, in tandem, could potentially find application in the production of chiral β-arylalanine building blocks, particularly, as refinements to the process are made that increase reaction flux, such as by selectively removing the desired (R)-β-arylalanine product from the reaction mixture. 2009 American Chemical Society.
- Cox, Brad M.,Bilsborrow, Joshua B.,Walker, Kevin D.
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supporting information; experimental part
p. 6953 - 6959
(2009/12/25)
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- Alkylation of N′-[(S)-1′-phenylethyl]-N-(diphenylmethylene)glycinamide using a phase transfer catalyst (PTC) for practical asymmetric syntheses of α-amino acid derivatives
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The chiral auxiliary mediated stereoselective alkylation reaction of N′-[(S)-1′-phenylethyl]-N-(diphenylmethylene)glycinamide (1) using a phase transfer catalyst (PTC) is described. Alkylation of 1 using 18-crown-6 as a PTC for liquid-solid extraction of KOH in toluene gives best results. This methodology provides a practical protocol for the preparation of a variety of enantio-enriched unnatural α-amino acid derivatives up to 83:17 enantiomeric ratio.
- Kim, Hyun Ju,Lee, Sang-Kuk,Park, Yong Sun
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p. 613 - 616
(2007/10/03)
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