- A practical and scalable system for heteroaryl amino acid synthesis
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A robust system for the preparation of β-heteroaryl α-amino acid derivatives has been developed using photoredox catalysis. This system operates via regiospecific activation of halogenated pyridines (or other heterocycles) and conjugate addition to dehydroalanine derivatives to deliver a wide range of unnatural amino acids. This process was conducted with good efficiency on large scale, the application of these conditions to amino ketone synthesis is shown, and a simple protocol is given for the preparation of enantioenriched amino acid synthesis, from a number of radical precursors.
- Aycock,Vogt,Jui
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p. 7998 - 8003
(2017/11/28)
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- Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway
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Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1cB elimination mechanism. All manner of things: A competing MIO-independent (MIO=4-methylideneimidazole-5-one) reaction pathway has been identified for phenylalanine ammonia lyases (PALs), which proceeds in a non-stereoselective manner, resulting in the generation of D-phenylalanine derivatives. The mechanism of D-amino acid formation is explored through isotopic-labeling studies and mutagenesis of key active-site residues.
- Lovelock, Sarah L.,Lloyd, Richard C.,Turner, Nicholas J.
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supporting information
p. 4652 - 4656
(2014/05/20)
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- Novel preparation of chiral α-amino acids using the Mitsunobu-Tsunoda reaction
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An efficient synthesis of racemic or optically active α-amino acids by modified-Mitsunobu alkylation of a racemic or chiral glycine template from alcohols was developed. Libraries of amino acids were prepared in moderate to good yield with good to high enantioselectivity. This simple method widens the scope for preparation of structurally diverse amino acids.
- Noisier, Anais F. M.,Harris, Craig S.,Brimble, Margaret A.
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supporting information
p. 7744 - 7746
(2013/09/02)
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- Fused purine derivatives
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A condensed purine derivative represented by Formula (I): wherein X—Y—Z represents R1N—C═O or N═C—W, R2 represents a hydrogen atom, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted alicyclic heterocyclic group or the like, n represents an integer of from 0 to 3, V1 represents a hydrogen atom, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group, V2 represents a substituted lower alkyl group or a substituted or unsubstituted aromatic heterocyclic group, and when V1 represents a hydrogen atom, a lower alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group, and for example, X—Y—Z represents R1aN—C═O and R2 represents a substituted lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alicyclic heterocyclic group, a halogen atom, a lower alkylthio group, —NR7R8, —CO2H, a lower alkoxycarbonyl group, —COHal, —CONR9R10 or —CHO, V2 may represent a lower alkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group; or a pharmacologically acceptable salt thereof.
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- Studies on polypeptides XXXII. Solid-phase synthesis of RNase S-peptide 1-14 analogues; replacement of histidine-12 by β-(2-pyridyl)-L-alanine and β-(4-pyridyl)-L-alanine
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The synthesis of two analogues of the N-terminal tetradecapeptide of ribonuclease A (RNase S-peptide 1-14), in which the active site histidine-12 residue is replaced by β-(2-pyridyl)-L-alanine and β-(4-pyridyl)-L-alanine, has been accomplished by the solid-phase method.The enantiomers of β-(2-pyridyl)alanine were obtained by chymotryptic hydrolysis of its racemic Nα-acetyl ethyl ester.The Boc derivative of both L-amino acids has been synthesized.
- Hoes, C.,Raap, J.,Bloemhoff, W.,Kerling, K. E. T.
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