- Synthesis of enantiopure free and N-benzyloxycarbonyl-protected 3-substituted homotaurines from naturally occurring amino acids
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Enantiopure N-benzyloxycarbonyl-protected and free 3-substituted homotaurines were synthesized from naturally occurring amino acids via N-benzyloxycarbonyl protection, Arndt-Eistert homologation, reduction, esterification with thioacetic acid, and oxidation with performic acid. The current method is a convenient, practical, and salt-free method for the synthesis of enantiopure 3-substituted homotaurine with moderate to good yields.
- Zheng, Yongpeng,Xu, Jiaxi
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p. 5197 - 5206
(2014/12/10)
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- Synthesis of enantiopure free and N-benzyloxycarbonyl-protected 3-substituted homotaurines from naturally occurring amino acids
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Enantiopure N-benzyloxycarbonyl-protected and free 3-substituted homotaurines were synthesized from naturally occurring amino acids via N-benzyloxycarbonyl protection, Arndt-Eistert homologation, reduction, esterification with thioacetic acid, and oxidation with performic acid. The current method is a convenient, practical, and salt-free method for the synthesis of enantiopure 3-substituted homotaurine with moderate to good yields.
- Zheng, Yongpeng,Xu, Jiaxi
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p. 5197 - 5206
(2014/07/08)
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- Facile synthesis of optically active imidazole derivatives
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Five optically active imidazole derivatives have been synthesized via a facile 4-step reaction sequence starting from commercially available and inexpensive N-Cbz amino acids. While microwave assisted condensation was unsuccessful, the condensation of the
- Marek, Ales,Kulhanek, Jiri,Ludwig, Miroslav,Bures, Filip
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p. 1183 - 1190
(2008/02/07)
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- Effective methods for the synthesis of N-methyl β-amino acids from all twenty common α-amino acids using 1,3-oxazolidin-5-ones and 1,3-oxazinan-6-ones
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N-Methyl β-amino acids are generally required for application in the synthesis of potentially bioactive modified peptides and other oligomers. Previous work highlighted the reductive cleavage of 1,3-oxazolidin-5-ones to synthesise N-methyl α-amino acids. Starting from α-amino acids, two approaches were used to prepare the corresponding N-methyl β-amino acids. First, α-amino acids were converted to N-methyl α-amino acids by the so-called '1,3-oxazolidin-5-one strategy', and these were then homologated by the Arndt-Eistert procedure to afford N-protected N-methyl β-amino acids derived from the 20 common α-amino acids. These compounds were prepared in yields of 23-57% (relative to N-methyl α-amino acid). In a second approach, twelve N-protected α-amino acids could be directly homologated by the Arndt-Eistert procedure, and the resulting β-amino acids were converted to the 1,3-oxazinan-6-ones in 30-45% yield. Finally, reductive cleavage afforded the desired N-methyl β-amino acids in 41-63% yield. One sterically congested β-amino acid, 3-methyl-3-aminobutanoic acid, did give a high yield (95%) of the 1,3-oxazinan-6-one (65), and subsequent reductive cleavage gave the corresponding AIBN-derived N-methyl β-amino acid 61 in 71% yield (Scheme 2). Thus, our protocols allow the ready preparation of all N-methyl β-amino acids derived from the 20 proteinogenic α-amino acids.
- Hughes, Andrew B.,Sleebs, Brad E.
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p. 2611 - 2637
(2007/10/03)
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- Chiral imidazole derivatives synthesis from enantiopure N-protected α-amino acids
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A route to the preparation of enantiopure ligands based on a 2-phenylimidazol ring is described. The stereogenic centre is placed into the chain bonded to the fourth carbon of the imidazole ring. The synthesis starts from inexpensive and readily available
- Bures, Filip,Kulhanek, Jiri
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p. 1347 - 1354
(2007/10/03)
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- Convenient and simple homologation of Nα-urethane protected α-amino acids to their β-homologues with concomitant o-nitrophenylesters formation
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The Wolff rearrangement of α-aminodiazoketones derived from Nα-urethane protected α-amino acids in presence of o-nitrophenol catalyzed by silver acetate at low temperature is described. The potential utility of the well-known ketene intermediat
- Ananda,Gopi,Suresh Babu
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p. 790 - 795
(2007/10/03)
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- Synthesis of optically active β-amino acid N-carboxyanhydrides
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(Equation presented) Methodology has been developed for the general synthesis of optically active β-amino acid N-carboxyanhydrides (β-NCAs) through cyclization of Nβ-Boc or Nβ-Cbz β-amino acids using phosphorus tribromide. The format
- Cheng, Jianjun,Ziller, Joseph W.,Deming, Timothy J.
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p. 1943 - 1946
(2007/10/03)
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- Convenient in situ synthesis of nonracemic N-protected β-amino aldehydes from β-amino acids. Applications in Wittig reactions and heterocycle synthesis
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N-Z-γ-amino alcohols derived from nonracemic β-amino acids are smoothly oxidised by manganese dioxide in acetonitrile to afford aldehydes which can be trapped in situ in Wittig reactions with carbonyl-substituted phosphoranes. The application of this methodology to the synthesis of the alkaloids (S)-(+)-N-BOC-coniine, (S)-(-)-coniceine and a pipecoline precursor is described.
- Davies, Simon B.,McKervey, M. Anthony
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p. 1229 - 1232
(2007/10/03)
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- Stereocontrolled synthesis of erythro N-protected α-amino epoxides and peptidyl epoxides
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N-protected α-amino epoxides of erythro configuration, derived from α-amino acids, were synthesized in a stereoselective manner. The erythro (2S,3S), configuration was achieved by the synthetic sequence: amino acid -> haloketone -> halohydrin -> epoxide. A mechanistic explanation for the observed stereoselectivity is presented. This stereoselective synthetic approach was applied to the synthesis of a variety of short peptidyl epoxides, bearing a predefined absolute configuration of the chiral epoxide moiety.
- Albeck, Amnon,Persky, Rachel
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p. 6333 - 6346
(2007/10/02)
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- Renin inhibitors containing isosteric replacements of the amide bond connecting the P3 and P2 sites
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Renin inhibitors having 13 different isosteres connecting the P3 and P2 positions have been prepared. Synthetic routes and in vitro activity exhibited by these compounds are discussed. The two most potent compounds, 47 and 48, contai
- Kaltenbronn,Hudspeth,Lunney,Michniewicz,Nicolaides,Repine,Roark,Stier,Tinney,Woo,Essenburg
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p. 838 - 845
(2007/10/02)
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- Inhibition of aminopeptidases by peptides containing ketomethylene and hydroxyethylene amide bond replacements
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Inhibitors of aminopeptidase enzymes have been prepared by the synthesis of peptide substrate analogues in which the scissile amide bond has been replaced with the hydrolytically stable ketomethylene (-COCH2-) and hydroxyethylene [-CH(OH)CHsub
- Harbeson,Rich
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p. 1378 - 1392
(2007/10/02)
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- Synthesis of gastrin antagonists, analogues of the C-terminal tetrapeptide of gastrin, by introduction of a β-homo residue
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A series of analogues of Boc-Trp-Leu-Asp-Phe-NH2, a potent gastrin agonist, were synthesized by introducing a β-homo residue in the sequence. These compounds were tested in vivo on acid secretion, in the anesthetized rat, and for their ability
- Rodriguez,Fulcrand,Laur,Aumelas,Bali,Martinez
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p. 522 - 528
(2007/10/02)
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