- Method for preparing aspartylcyclohexyla laninamide
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Disclosure is a method for preparing α-aspartyl-β-cyclohexylalaninamide, comprising carrying out a first step of amide formation of an α-aspartyl phenylamine ester of general formula (II) wherein: R is a C1-C4alkyl radical, and then
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Page column 6-7
(2008/06/13)
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- Method for preparing aspartylcyclohexyla laninamide
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Disclosure is a method for preparing α-aspartyl-β-cyclohexylalaninamide, comprising carrying out a first step of amide formation of an α-aspartyl phenylamine ester of general formula (II) wherein: R is a C1-C4 alkyl radical, and then
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- Protected-mode Synthesis of N-Linked Glycopeptides: Single-step Preparation of Building Blocks as Peracetyl Glycosylated NαFmoc Asparagine OPfp Esters
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The preparation of Nα-(fluoren-9-ylmethoxycarbonyl)asparagine pentafluorophenyl esters (Nα-Fmoc-Asn-OPfp) glycosylated with per-O-acetylated β-D-glucose, N-acetyl-β-D-glucosamine, β-D-mannose, 4-O-β-D-glucopyranosyl-β-D-glucose (cellobiose), 4-O-β-D-galactopyranosyl-β-D-glucose (lactose) and 4-O-α-D-glucopyranosyl-β-D-glucose (maltose) is described.The per-O-acetylated glycosylamines were treated selectively with the key compound Nα-Fmoc-Asp(Cl)-OPfp 2, to give, in a single step, the glycosylated building blocks.The acid chloride 2 was prepared in a quantitative one-pot reaction from commercially available Nα-Fmoc-Asp(OBut)-OPfp 1.The acid stability of the N-glycosidic linkage was investigated.The building block 7, containing a maltose moiety, was used in the synthesis of a glycosylated D-Ala1 Peptide-T amide analogue 14.CD spectra were recorded in 85 percent TFE.All compounds were fully characterized by (1)H and (13)C NMR spectroscopy.
- Christiansen-Brams, Ida,Meldal, Morten,Bock, Klaus
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p. 1461 - 1472
(2007/10/02)
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- Aspartate Racemization in Synthetic Peptides. Part 2. Tendency to Racemization of Aminosuccinyl Residue
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Aminosuccinyl (Asu) peptides, containing a strained ring system, are very vulnerable to epimerization and, during their formation, even as transients, in the presence of nucleophilic and nonnucleophilic bases, partial epimerization occurs.In the presence
- Schoen, Istvan,Szirtes, Tamas,Rill, Attila,Balogh, Gabor,Vadasz, Zsolt,et al.
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p. 3213 - 3223
(2007/10/02)
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- PAPAIN-CATALYZED FRAGMENT SYNTHESIS OF PROTECTED CHOLECYSTOKININ DERIVATIVES
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Sodium salts of methyl esters of N-tert-butyloxycarbonyl-β-tert-butylaspartyl-O4-sulfotyrosine (II) or N-tert-butyloxycarbonyl-O4-sulfotyrosine (III) were condensed with amino components derived from peptide amides IVb-IVe and IVg (simulating the carboxy-terminal part of cholecystokinin) under catalysis with papain.Rates and yields of conversion of these peptides to the corresponding derivatives Ib-If were compared with the results reported previously for analogous papain-catalyzed fragment synthesis of the protected carboxy-terminal octapeptide of cholecystokinin Ia.In the condensation reactions with the individual amino components quantitative changes were observed in the ability of papain to catalyze the peptide bond synthesis which appeared as differences in the maximum yield (and the time required for achieving it) of the condensation reaction, monitored by HLPC.The observed differences are related not only with the distance of the amino acid substitution from the P'1 subsite in the given amino component but also with the side-chain structure of the substituting amino acid.
- Cerovsky, Vaclav,Pirkova, Jana,Majer, Pavel,Slaninova, Jirina,Hlavacek, Jan
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p. 1873 - 1882
(2007/10/02)
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- Method relating to preparation of aspartyl peptides
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The present invention is directed to a composition and method relating to the preparation of aspartyl peptides having the general formula: STR1 where the radical-NHR represents an amino acid or peptide group. In the method, a β-monoester of aspartic acid having the general formula: STR2 where R1 represents a hydrocarbon-containing radical, is reacted with a β-dicarbonyl compound, preferably ethylacetoacetate to protect the aspartyl amino group and form an enamine. The enamine is then coupld to an amino acid or peptide, following which any protecting groups are removed to yield α-aspartyl peptides without any β-isomer. In its composition aspects, the present invention is directed to novel enamines resulting from reaction of the β-monoester of aspartic acid with a β-dicarbonyl compound.
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- Studies on Peptides. CXLIII. Evaluation of β-Menthylaspartate for Peptide Synthesis
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The β-l-menthyl ester of aspartic acid, Asp(OMen), was found to be stable to trifluoroacetic acid (TFA) in an ice-bath for 3 h, but to be cleaved by HF or 1 M trifluoromethanesulfonic acid-thioanisole in TFA in an ice-bath within 60 min.Asp(OMen) was employed for the synthesis of tetragastrin, for which the use of diphenylsulfide, as an additional scavenger, is recommended to accelerate the acidolytic cleavage of this protecting group.This protecting group is superior to other available protecting groups so far examined in terms of suppression of base-catalyzed succinimide formation.Keywords - β-menthylaspartate; base-catalyzed succinimide formation; acid-catalyzed succinimide formation; hydrogen fluoride deprotection; trifluoromethanesulfonic acid deprotection; cation scavenger; diphenylsulfide; tetragastrin
- Yajima, Haruaki,Futaki, Shiroh,Otaka, Akira,Yamashita, Takeyoshi,Funakoshi, Susumu,et. al.
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p. 4356 - 4361
(2007/10/02)
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