- Component-selective and stereocontrolled one-step three-component reaction among aldehydes, amines, and allenyl boronic acids or allenyl pinacolboronates
-
A one-step, three-component condensation of allenyl boronic acids or allenyl pinacolboronates with amines and aldehydes affords α-allenyl or α-propargyl α-amino acids and anti-β-amino alcohols. This process gives the allenyl or propargyl product depending on the amine and boron components. Secondary amines generate exclusively α-allenyl α-amino acids, while primary aliphatic amines lead to α-propargyl α-amino acids. Secondary aliphatic amines react with chiral α-hydroxy aldehydes and allenyl boron derivatives to form stereoselectively allenyl anti-β-amino alcohol products.
- Liepouri, Fotini,Bernasconi, Giovanni,Petasis, Nicos A.
-
-
Read Online
- Catalytic amino acid production from biomass-derived intermediates
-
Amino acids are the building blocks for protein biosynthesis and find use in myriad industrial applications including in food for humans, in animal feed, and as precursors for bio-based plastics, among others. However, the development of efficient chemical methods to convert abundant and renewable feedstocks into amino acids has been largely unsuccessful to date. To that end, here we report a heterogeneous catalyst that directly transforms lignocellulosic biomass-derived α-hydroxyl acids into α-amino acids, including alanine, leucine, valine, aspartic acid, and phenylalanine in high yields. The reaction follows a dehydrogenation-reductive amination pathway, with dehydrogenation as the rate-determining step. Ruthenium nanoparticles supported on carbon nanotubes (Ru/CNT) exhibit exceptional efficiency compared with catalysts based on other metals, due to the unique, reversible enhancement effect of NH3 on Ru in dehydrogenation. Based on the catalytic system, a two-step chemical process was designed to convert glucose into alanine in 43% yield, comparable with the well-established microbial cultivation process, and therefore, the present strategy enables a route for the production of amino acids from renewable feedstocks. Moreover, a conceptual process design employing membrane distillation to facilitate product purification is proposed and validated. Overall, this study offers a rapid and potentially more efficient chemical method to produce amino acids from woody biomass components.
- Deng, Weiping,Wang, Yunzhu,Zhang, Sui,Gupta, Krishna M.,Hülsey, Max J.,Asakura, Hiroyuki,Liu, Lingmei,Han, Yu,Karp, Eric M.,Beckham, Gregg T.,Dyson, Paul J.,Jiang, Jianwen,Tanaka, Tsunehiro,Wang, Ye,Yan, Ning
-
p. 5093 - 5098
(2018/05/23)
-
- Nitrosation and analysis of amino acid derivatives by isocratic HPLC
-
The objective of this study was to characterize the nitrosation of the classical amino acids by N2O3. Nitrosation of amino acids results in the formation of mainly α-hydroxy-acids that are suitable for isocratic HPLC analysis and subsequent quantification of amino acids in biological samples. The method is particularly suitable for detection of amino acids in e.g. fermentation media as the α-hydroxy-acids can be quantified in parallel to a variety of other organic substrates and products. The amino acids were transformed into their corresponding α-hydroxy-acids in acidic KNO2 solutions. The reactions were terminated by NaOH addition and the α-hydroxy-acids separated by isocratic HPLC and quantified by refractive index or UV absorption detection. Nitrosation of 18 of the classical amino acids; glycine, l-alanine, l-valine, l-leucine, l-isoleucine, l-methionine, l-serine, l-threonine, l-asparagine, l-glutamine, l-aspartic acid, l-glutamic acid, l-proline, l-cysteine, l-phenylalanine, l-lysine, l-tyrosine, and l-tryptophane formed detectable nitrosation products. l-Lysine, however, needed incubation in 96 mM formic acid to produce a detectable product, while l-phenylalanine had to be incubated in 120 mM HNO3 and 100 mM HCl. Optimal reaction conditions for most amino acids included 40 min of incubation of up to 5 g L-1 amino acid in 160 mM KNO2 in 100 mM HCl at 45 °C to maximize product yields.
- Ulusoy, Songül,Ulusoy, Halil Ibrahim,Pleissner, Daniel,Eriksen, Niels Thomas
-
p. 13120 - 13128
(2016/02/12)
-
- DERMAL COMPOSITIONS CONTAINING UNNATURAL HYGROSCOPIC AMINO ACIDS
-
Unnatural, hygroscopic amino acids are useful to enhance the moisture retention and uptake properties of skin. In particular, such amino acids are N-hydroxyserine, N- hydroxyglycine, L-homoserine,alpha-hydroxyglycine, 2-(aminooxy) -2-hydroxyacetic acid, 2-hydroxy-2-(hydroxyamino) acetic acid, 2- (aininooxy)acetic acid, and combinations thereof.
- -
-
Page/Page column 26
(2014/05/24)
-
- Chelate derivatives as protectors against tissue injury
-
Derivatives useful in the protection of living organisms against damage due to free radical reactions derived from methoxypolyethylene glycols (MPEG), which are modified by chemically attaching chelating groups in an amide or amine linkage to the nonmethyl end of the polymer. Such chelating groups include ethylene-diamine tetraacetic acid (EDTA), diethylene triamine pentaacetic acid (DTPA), and ethylene glycol aminoethyl ether tetraacetic acid (EGTA), and pharmacologically acceptable salts or esters thereof.
- -
-
-
- The Reaction of Glyoxylic Acid with Ammonia Revisited
-
Upon addition of ammonia or an alkylamine to glyoxylic acid an ammonium derivative of glyoxylic acid precipitates quantitatively.With the use of solid-state 13C and 15N NMR spectroscopy, it is shown that adducts of glyoxylic acid and ammonia or the alkylamine are obtained.These compounds are not stable in aqueous solution.The compositions of the aqueous solutions have been investigated by 1H, 13C, 15N, and 17O NMR.Under basic conditions hexahydro-s-triazine-2,4,6-tricarboxylate is the predominant species in a solution of the adduct of ammonia and glyoxylic acid, whereas upon acidification (pH 6) glyoxylate is the only organic species.In a basic solution of the adduct of ethylamine and glyoxylic acid N-ethyliminoacetate is the only species.The N-methyl adduct shows an intermediate behavior: both the hexahydrotriazine and the imine are observed.Under acidic conditions deamination to glyoxylate always occurs.Intermediates in the reaction of glyoxylic acid and ammonia could be detected with 1H NMR, when the reaction was performed with an excess of ammonia.The mechanism of these reactions is discussed.
- Hoefnagel, Anthonius J.,Bekkum, Herman van,Peters, Joop A.
-
p. 3916 - 3921
(2007/10/02)
-