Search results for "dipeptide"
showing 10 items of 99 documents
Synthese von Giycopeptiden: Selektive C-terminale Deblockierung und Peptidkettenverlängerung an Glucosylserin-Derivaten
1983
Benzyloxycarbonyl-(Z-)serin-2-bromethylester (3b) wird mit 2,3,4,6-Tetra-O-benzoyl-α-D-gluco-pyranosylbromid (14) zum Glucosylserinester 15 verknupft. Nach Umwandlung in den entsprechenden 2-Iodethylester 23 wird die Carboxygruppe durch Eliminierung mit Zink selektiv deblockiert. Dabei bleiben die Z- und die Kohlenhydrat-Schutzgruppen sowie die empfindliche O-glycosidische Bindung unverandert erhalten. Das Glycosyl-Z-serin 24 reagiert mit Aminosaure-2-bromethylestern 2 zu geschutzten Glycodipeptid-2-bromethylestern 18, die nach selektiver Carboxydeblockierung zu Glycotripeptidestern 25 C-terminal verlangert werden. Wahrend geschutzte Serin-Dipeptide 5 mit 14 zu Konjugaten 18 glycosyliert we…
N-p-Amino- and N-p-nitro-phenylsulfonyl derivatives of dipeptides, a new family of ligands for copper(II). Potentiometric and spectroscopic studies
1995
The co-ordination ability of four dipeptide analogues substituted on the N-terminal amino group with p-nitrophenylsulfonyl (nps-Ala-Ala and nps-Ala-His) and p-aminophenylsulfonyl (aps-Ala-Ala and aps-Ala-His) groups was studied by potentiometric and spectroscopic (UV/VIS absorption, CD and EPR) techniques. The N-terminal sulfonyl substituent drastically changes the acidity of the sulfonamide proton making nitrogen very efficient in binding to CuII. The sulfonamide nitrogen having pK between 9 and 11 does not need any anchoring binding group to form complexes with CuII. The para substituent on the phenyl ring (amino or nitro) influences very strongly the acidity of the sulfonamide proton. Th…
Trifluoracetylierung von aminosäureestern und dipeptidestern mit N-trifluoracetyl-polyamid 66.
1981
N-Trifluoroacetyl-Polyamid 66 (1) is used for the trifluoroacetylation of amino acid- and dipeptide esters. Advantages and limitations of the polymeric reagent compared with low molecular trifluoroacetylating reagents are discussed. A mixture of amino acid methyl esters can be converted by 1 to the N-trifluoroacetyl derivatives, which are separated and identified by gas chromatography.
Synthesis of peptides with α,β‐dehydroamino acids, III. Debenzyloxycarbonylation and detrifluoroacetylation of dehydroalanine and dehydrophenylalanin…
1985
The removal of amino protecting groups from a series of twelve model Z-3) or TFA-dipeptides of dehydroalanine and (Z)-dehydrophenylalanine was investigated. During this deprotection, peptides with Δ Ala are prone to side reactions to a higher extent than those with Δ Phe. Therefore it is interesting to note that from the Δ Ala peptides, the Z group can be split off in preparative manner with HCO2NH4 in the presence of Pd C (Table 4). Synthese von Peptiden mit α,β-Dehydroaminosauren, III.– Debenzyloxycarbonylierung und Detrifluoracetylierung von Dehydroalanin- und Dehydrophenylalanin-Peptiden An einer Serie von zwolf Z-3) oder TFA-Modellpeptiden mit Dehydroalanin und (Z)-Dehydrophenylalanin …
ChemInform Abstract: O-Boronato- and o-Trifluoroborato-Phosphonium Salts Supported by L-α-Amino Acid Side Chain.
2015
The synthesis of o-boronato- and o-trifluoroborato–phosphonium salts supported by the l-amino acid side chain is described. The synthesis of these new class of amino acid derivatives was achieved by stereoselective quaternization of o-(pinacolato)boronatophenylphosphine with β- or γ-iodo amino acid derivatives which are prepared from l-serine or l-aspartic acid, respectively. The quaternization of the phosphine was performed using either iodo amino ester or carboxylic acid derivatives. In addition, free carboxylic acid and amine derivatives were obtained by saponification or HCl acidolysis of o-boronato–phosphonium amino esters, respectively. The usefulness of these compounds in peptide cou…
Michael additions to double bonds of esters of N-protected (s)-phenylalanyldehydroalanine (X-(s)-Phe-ΔAla-OMe) and its phosphonic acid counterpart (X…
2017
Electrophilic addition of amines, thiols and bromide to the double bonds of model dehydrodipeptides and dehydrophosphonodipeptide was studied. The double bond in these two classes of peptides reacted similarly and gave the same products. These results indicate that dehydropeptides are very good candidates as substrates for modifications of peptide side-chains.
Structure of an [alpha],[beta]-unsaturated dipeptide, racemic N-[(phenylmethoxy)carbonyl]phenylalanyl-[Delta]2-phenylalanine
1987
Synthesis of Peptides with α,β-Dehydroamino Acids, II. Synthesis oftert-Butyloxycarbonyldipeptides of Dehydroalanine and Dehydrophenylalanine
1985
Condensation of amides of Boc-amino acids3) with pyruvic acid leads to Boc-dipeptides 1 – 3 of dehydroalanine and 1-Boc-5-alkyl-2-methyl-4-oxo-2-imidazolidinecarboxylic acids 8 – 10. The amides, however, do not condense with phenylpyruvic acid. Boc-dipeptides of dehydroalanine (1 – 3) and dehydrophenylalanine (4 – 7) are synthesized using (Boc)2O and dehydrodipeptides with a free unmasked N-terminal amino group. Synthese von Peptiden mit α,β-Dehydroaminosauren, II1). – Synthese von tert-Butyloxycarbonyldipeptiden von Dehydroalanin und Dehydrophenylalanin2) Die Kondensation von Boc-Aminosaureamiden3) mit Brenztraubensaure fuhrt zu Boc-Dipeptiden 1 – 3 des Dehydroalanins und 1-Boc-5-alkyl-2-m…
Der 2-(4-pyridyl)Ethoxycarbonyl-(4-Pyoc)-rest - eine hydrophile, säure- und basenstabile aminoschutzgruppe für die peptidsynthese
1984
Abstract The title amino blocking function is stable under basic and acidic conditions frequently used in the peptide synthesis. Its hydrophilicity permits an effective peptide synthesis in water. After the easy conversion to the pyridinium form the 4-Pyoc group can be removed by morpholine.
Oligopeptide der β-Carbolin-3-carbonsäure - Synthese und Affinität zu Benzodiazepinrezeptoren
1987
Es wurden Oligopeptide der β-Carbolin-3-carbonsaure dargestellt und deren Affinitat zum Benzodiazepinrezeptor in Mausehirn-Membranen bestimmt. Uber Struktur-Affinitatsbeziehungen wird berichtet. Oligopeptides of β-Carboline-3-carboxylic Acid - Synthesis and Benzodiazepine Receptor Affinity Oligopeptides of β-carboline-3-carboxylic acid were prepared and tested with respect to their affinity for the benzodiazepine receptor in mouse brain membranes. Structure-affinity relationships are reported.