- Potassium Thioacids Mediated Selective Amide and Peptide Constructions Enabled by Visible Light Photoredox Catalysis
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A remarkable visible-light-promoted photoredox catalytic methodology involved with amines and eco-friendly potassium thioacids for amide formation was uncovered. This approach can mimic the natural coenzyme acetyl-CoA to selectively acylate amines without affecting other functional groups such as alcohols, phenols, esters, among others. The developed strategy may hold great potential for a comprehensive display of biologically interesting peptide synthesis and amino acid modification through a diacyl disulfide intermediate.
- Liu, Hongxin,Zhao, Liyun,Yuan, Yunfei,Xu, Zhifang,Chen, Kai,Qiu, Shengxiang,Tan, Haibo
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p. 1732 - 1736
(2016/03/15)
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- Selectivity in Carbonic Anhydrase Catalyzed Hydrolysis of Standard N-Acetyl-DL-amino Acid Methyl Esters
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Carbonic anhydrase-catalyzed hydrolysis of some standard N-acetyl-DL-amino acid methyl esters proceeds with high enantioselectivity.This enzyme hydrolyses selectively D amino acid derivatives in contrast to proteases which have a L stereoselectivity. Key Words: carbonic anhydrase, hydrolysis, N-acetyl-DL-amino acid methyl esters, enantioselectivity.
- Chenevert, Robert,Rhlid, Rachid Bel,Letourneau, Martin,Gagnon, Rene,D'Astous, Linda
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p. 1137 - 1140
(2007/10/02)
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- Racemization of Optically Active Aromatic N-Acetylamino Acids and Asymmetric Transformation of N-Acetyl-2-(4-hydroxyphenyl)glycine via Salt Formation with Optically Active α-Methylbenzylamine
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The racemization rates of N-acetyl-(S)-tyrosine, N-acetyl-(S)-phenylalanine, N-acetyl-(R)-2-(4-hydroxyphenyl)glycine , N-acetyl-(R)-2-phenylglycine, and N-acetyl-(S)-alanine were measured by use of (RS)-α-methylbenzylamine as base-catalyst.The first-order rate constant for racemization tended to increase with an increase in the polar substituent constant of the N-acetylamino acid side chain.The racemization appeared to be subject to the inductive effect by the side chain.An asymmetric transformation of (RS)-AcHpg by using (R)-MBA, based on the result of racemization, gave an optically pure salt of (R)-AcHpg with (R)-MBA by successive use of the filtrate as the solvent.Optically pure (R)-2-(4-hydroxyphenyl)glycine was separated from the salt in 87-90percent yield based on the starting (RS)-AcHpg.In addition, the asymmetric transformation of (R)-AcHpg was achieved by using (S)-MBA to give optically pure (S)-Hpg in 80percent yield after purification of the salt of (S)-AcHpg with (S)-MBA followed by hydrolysis.
- Shiraiwa, Tadashi,Sakata, Shinji,Natsuyama, Hisashi,Fujishima, Keiko,Miyazaki, Hideya,et al.
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p. 965 - 970
(2007/10/02)
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- Cosmetic sunscreen product for the face and body
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Cosmetic sunscreen products which contain a tyrosine derivative of the formula: STR1 in which R1 is H or CH3 --(CH2)x, with X being 1 to 20, and R2 is CH3 CO-- or CH3 --(CH2)y --CO, with Y being 1 to 20, provide a long lasting and dark, natural tan after a short exposure to sunlight. The sunscreen product may contain an activator which is an alkali metal or alkaline earth metal salt of adenosine-5'-tri-, di-, or monophosphoric acid and mixtures thereof with an alkali metal or alkaline earth metal hydrogen phosphate.
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