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Dehydroamino Acids (dehydroamino + acid)
Terms modified by Dehydroamino Acids Selected AbstractsChemInform Abstract: Enantioselective Synthesis of ,,,-Disubstituted ,-Amino Acids by Rh-Catalyzed [2 + 2 + 2] Cycloaddition of 1,6-Diynes with Protected Dehydroamino Acid.CHEMINFORM, Issue 46 2008Ken Tanaka Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Polymer-Supported Phosphoramidites: Highly Efficient and Recyclable Catalysts for Asymmetric Hydrogenation of Dimethylitaconate and Dehydroamino Acids and Esters.CHEMINFORM, Issue 37 2003Simon Doherty Abstract For Abstract see ChemInform Abstract in Full Text. [source] An improved procedure for the synthesis of dehydroamino acids and dehydropeptides from the carbonate derivatives of serine and threonine using tetrabutylammonium fluorideJOURNAL OF PEPTIDE SCIENCE, Issue 3 2010Ramesh Ramapanicker Abstract Dehydroamino acids are important precursors for the synthesis of a number of unnatural amino acids and are structural components in many biologically active peptide derivatives. However, efficient synthetic procedures for their production in large amounts and without side reactions are limited. We report here an improved procedure for the synthesis of dehydroalanine and dehydroamino butyric acid from the carbonate derivatives of serine and threonine using TBAF. The antiselective E2 elimination of the carbonate derivatives of serine and threonine using TBAF is milder and more efficient than other available procedures. The elimination reaction is completed in less than 10 min with various carbonate derivatives studied and the methodology is very efficient for the synthesis of dehydroamino acids and dehydropeptides. The procedure thus provides an easy access to key synthetic precursors and can be used to introduce interesting structural elements to designed peptides. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis of Novel Chiral and Acentric Coordination Polymers by the Reaction of Zinc or Cadmium Salts with Racemic 3-Pyridyl-3-aminopropionic AcidCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2004Zhi-Rong Qu Abstract Under hydrothermal (solvothermal) reaction conditions chiral compounds 1, 2, and 3 and one acentric compound 4 were obtained by the reaction of Zn2+ or Cd2+ with racemic 3-(3-pyridyl)-3-aminopropionic acid (rac -HPAPA). Compounds 1 and 2 crystallized in chiral space group P212121. At 105,°C, racemic 3-pyridyl-3-aminopropionic acid (rac -HPAPA) reacted with Zn(ClO4)2,6,H2O and dehydrogenated in situ to form the first chiral coordination polymer [Zn{(E)-3-C5H4NC(NH2)CHCOO}]ClO4 (1) with a ,-dehydroamino acid. Beyond 120,°C, the reaction of rac -HPAPA with Zn(ClO4)2,6,H2O deaminates in situ to form chiral coordination polymer [Zn{(E)-3-C5H4NCHCHCOO}(OH)] (2). At relatively low temperatures (70,°C), the solvothermal reaction of Zn(NO3)2,6,H2O with rac -HPAPA in methanol does not lead to any change in the ligand and results in the formation of a chiral (P212121) coordination polymer [Zn(papa)(NO3)] (3). The same reaction of Cd(ClO4)2,6,H2O with HPAPA also does not lead to any change in ligand and results in the formation of noncentric (Cc) coordination polymer [Cd(papa)(Hpapa)]ClO4,H2O (4). The network topology of both 1 and 3 is 10,3a, while 2 has a diamondoid-like (KDP-like, KDP=potassium dideuterophosphate) network. Particularly interesting from a topological perspective is that 4 has an unprecedented three-dimensional network. Compounds 1, 2, 3, and 4 are all second harmonic generation (SHG) active with 1 exhibiting the strongest response, while only 4 also displays good ferroelectric properties. [source] Synthesis of Novel Amino Acids and Dehydroamino Acids Containing the Benzo[b]thiophene MoietyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2003Ana S. Abreu Abstract Several novel amino acids and dehydroamino acids containing the benzo[b]thiophene moiety were prepared by Michael addition or sequential Michael addition and palladium-catalyzed C,C or C,N cross couplings. The substrates for Michael addition were the methyl esters of N,N -bis(tert -butyloxycarbonyl)dehydroalanine [Boc2,,Ala,OMe] and N -(4-toluenesulfonyl)- N -(tert -butyloxycarbonyl)dehydroalanine [Tos,,Ala(N -Boc),OMe], and the nucleophiles were aromatic thiols and 3-iodobenzylamine. The addition of mercaptobenzo[b]thiophenes directly to Tos,,Ala(N -Boc),OMe gave stereoselectively, in good yields, the E -isomer of the corresponding dehydrocysteine. When thiophenols and 3-iodobenzylamine were used as nucleophiles the presence of an additional function (halogen or amine) allowed a subsequent palladium-catalyzed cross-coupling reaction with functionalized benzo[b]thiophenes (boronic acids, a halogen or an amine). Using this strategy, several racemic amino acid and dehydroamino acid derivatives, which are linked to the benzo[b]thiophene moiety by an aromatic spacer, were obtained in good yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] An improved procedure for the synthesis of dehydroamino acids and dehydropeptides from the carbonate derivatives of serine and threonine using tetrabutylammonium fluorideJOURNAL OF PEPTIDE SCIENCE, Issue 3 2010Ramesh Ramapanicker Abstract Dehydroamino acids are important precursors for the synthesis of a number of unnatural amino acids and are structural components in many biologically active peptide derivatives. However, efficient synthetic procedures for their production in large amounts and without side reactions are limited. We report here an improved procedure for the synthesis of dehydroalanine and dehydroamino butyric acid from the carbonate derivatives of serine and threonine using TBAF. The antiselective E2 elimination of the carbonate derivatives of serine and threonine using TBAF is milder and more efficient than other available procedures. The elimination reaction is completed in less than 10 min with various carbonate derivatives studied and the methodology is very efficient for the synthesis of dehydroamino acids and dehydropeptides. The procedure thus provides an easy access to key synthetic precursors and can be used to introduce interesting structural elements to designed peptides. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. [source] Investigation of the Substrate Specificity of Lacticin 481 Synthetase by Using Nonproteinogenic Amino AcidsCHEMBIOCHEM, Issue 5 2009Matthew R. Levengood Abstract One enzyme, many substrates. The substrate specificity of a lantibiotic biosynthetic enzyme, lacticin 481 synthetase, was probed by using synthetic prepeptides containing a variety of nonproteinogenic amino acids, including unnatural ,-amino acids, ,-amino acids, D -amino acids, and peptoids. Lantibiotics are peptide antimicrobial compounds that are characterized by the thioether-bridged amino acids lanthionine and methyllanthionine. For lacticin 481, these structures are installed in a two-step post-translational modification process by a bifunctional enzyme, lacticin 481 synthetase (LctM). LctM catalyzes the dehydration of Ser and Thr residues to generate dehydroalanine or dehydrobutyrine, respectively, and the subsequent intramolecular regio- and stereospecific Michael-type addition of cysteines onto the dehydroamino acids. In this study, semisynthetic substrates containing nonproteinogenic amino acids were prepared by expressed protein ligation and [3+2]-cycloaddition of azide and alkyne-functionalized peptides. LctM demonstrated broad substrate specificity toward substrates containing ,-amino acids, D -amino acids, and N -alkyl amino acids (peptoids) in certain regions of its peptide substrate. These findings showcase its promise for use in lantibiotic and peptide-engineering applications, whereby nonproteinogenic amino acids might impart improved stability or modulated biological activities. Furthermore, LctM permitted the incorporation of an alkyne-containing amino acid that can be utilized for the site-selective modification of mature lantibiotics and used in target identification. [source] | ||||||||||