- Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation
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The preparation of peptide fragments containing dehydrovaline and dehydroisoleucine moieties present in the antibiotic myxovalargin is reported. Peptide formation is based on a copper-mediated C-N cross-coupling protocol between an acyl amide and a peptidic vinyl iodide. The presence of a neighboring arginine in the vinyl iodide posed a challenge with respect to the choice of the protecting group and the reaction conditions. It was found that ornithine - a suitable precursor - is better suited than arginine for achieving good yields for the C-N cross-coupling reaction. The optimized conditions were utilized for the synthesis of peptides 32, 33, 39 and 40 containing a neighboring ornithine as well as for the tripeptide 44 containing dehydroisoleucine with the correct stereochemistry.
- Gille, Franziska,Kirschning, Andreas
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supporting information
p. 564 - 570
(2016/04/08)
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- Guanidine-acylguanidine bioisosteric approach in the design of radioligands: Synthesis of a tritium-labeled NG-propionylargininamide ([3H]-UR-MK114) as a highly potent and selective neuropeptide Y Y1 receptor antagonist
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Synthesis and characterization of (R)-Nα-(2,2- diphenylacetyl)-N-(4-hydroxybenzyl)-Nω-([2,3- 3H]-propanoyl)-argininamide ([3H]-UR-MK114), an easily accessible tritium-labeled NPY Y1 receptor (Y1R) antagonist (KB: 0.8 nM, calcium assay, HEL cells) derived from the (R)-argininamide BIBP 3226, is reported. The radioligand binds with high affinity (KD, saturation: 1.2 nM, kinetic experiments: 1.1 nM, SK-N-MC cells) and selectivity for Y1R over Y2, Y 4, and Y5 receptors. The title compound is a useful pharmacological tool for the determination of Y1R ligand affinities, quantification of Y1R binding sites, and autoradiography.
- Keller, Max,Pop, Nathalie,Hutzler, Christoph,Beck-Sickinger, Annette G.,Bernhardt, Günther,Buschauer, Armin
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supporting information; experimental part
p. 8168 - 8172
(2009/12/07)
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- Aqueous phosphoric acid as a mild reagent for deprotection of tert-butyl carbamates, esters, and ethers
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(Chemical Equation Presented) Aqueous phosphoric acid (85 wt %) is an effective, environmentally benign reagent for the deprotection of tert-butyl carbamates, tert-butyl esters, and tert-butyl ethers. The reaction conditions are mild and offer good selectivity in the presence of other acid-sensitive groups, including CBZ carbamates, azetidine, benzyl and methyl esters, TBDMS, and methyl phenyl ethers. The mildness of the reaction is further demonstrated in the synthesis of clarithromycin derivative 4, in which a tert-butyl ester is removed in the presence of cyclic carbamate, lactone, ketal, acetate ester, and epimerizable methyl ketone functionalities. The reaction preserves the stereochemical integrity of the substrates. The reactions are high yielding, and the workup is convenient.
- Li, Bryan,Berliner, Martin,Buzon, Richard,Chiu, Charles K.-F.,Colgan, Stephen T.,Kaneko, Takushi,Keene, Nandell,Kissel, William,Le, Tung,Leeman, Kyle R.,Marquez, Brian,Morris, Ronald,Newell, Lisa,Wunderwald, Silke,Witt, Michael,Weaver, John,Zhang, Zhijun,Zhang, Zhongli
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p. 9045 - 9050
(2007/10/03)
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- Different Acyl Specificity between Mold and Kidney Acylases: Correlation of Hydrolytic Rate to Molecular Size and Electronegative Property of Acyl Group in Acyl-L-phenylalanine Hydrolysis
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A series of acyl-L-phenylalanines were hydrolyzed by mold and hog kidney acylases.The formyl was found to be the most susceptible for mold acylase, and the butyryl for kidney acylase, indicating the different preferences of these acylases in molecular size and electronegative property of acyl group of substrates.
- Kang, Shinwon,Minematsu, Yoshihiro,Shimohigashi, Yasuyuki,Waki, Michinori,Izumiya, Nobuo
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p. 575 - 576
(2007/10/02)
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