Synthesis of peptides with α,β‐dehydroamino acids, V. coupling experiments with C‐terminal dehydrophenylalanine and dehydroalanine residues

N-Protected model dipeptides of C-terminal (Z)-ΔPhe and ΔAla couple with glycine esters after activation with either diphenyl phosphorazidate (DPPA), N-cyclohexyl-N′-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate (WSC), N,N′-dicyclohexylcarbodiimide + 1-hydroxybenzotriazole (DCC + HOBt), or the mixed anhydride (MA) with isobutyl chlorocarbonate to give in good or mostly moderate yields the (Z)-ΔPhe-containing tripeptides 1 – 9 and ΔAla-containing tripeptides 11 – 19, respectively. In the MA and DPPA methods, further acylation products 20a – d are formed to a great extent, expecially during the ΔAla peptide syntheses. (E)-TFA-Gly-ΔPhe and Gly-OtBu, irrespective of the activati…

SYNTHESIS OFt-BUTOXYCARBONYL AND BENZYLOXYCARBONYL AMINO ACID AMIDES

Synthesis of peptides with α,β‐dehydroamino acids, I. synthesis of N‐benzyloxycarbonyl and N‐trifluoroacetyl dipeptides of dehydroalanine and dehydrophenylalanine

Condensation of amides of N-(benzyloxycarbonyl)- and N-(trifluoroacetyl)amino acid with pyruvic and phenylpyruvic acid yields, in the presence of p-toluenesulfonic acid as a catalyst, N-(benzyloxycarbonyl)- and N-(trifluoroacetyl)dehydro dipeptides with C-terminal Δ Ala and ΔPhe, respectively (Table 2 and 3). Synthese von Peptiden mit α,β-Dehydroaminosauren, I. - Synthese von N-(Benzyloxycarbonyl)-und N-(Trifluoracetyl) dipeptiden von Dehydroalanin und Dehydrophenylalanin Die Kondensation von Nα-(Benzyloxycarbonyl)- und Nα-(Trifluoracetyl)aminosaureamiden mit Brenztrauben- und Phenylbrenztraubensaure in Gegenwart von p-Toluolsulfonsaure als Katalysator fuhrt zu N-(Benzyloxycarbonyl)- und N-…

Synthesis of Peptides with α,β-Dehydroamino Acids, II. Synthesis oftert-Butyloxycarbonyldipeptides of Dehydroalanine and Dehydrophenylalanine

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…

Structure of an [alpha],[beta]-unsaturated dipeptide, racemic N-[(phenylmethoxy)carbonyl]phenylalanyl-[Delta]2-phenylalanine

Overview of the JET results with the ITER-like wall

Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Zeff (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. T…

Synthesis of peptides with α,β‐dehydroamino acids, III. Debenzyloxycarbonylation and detrifluoroacetylation of dehydroalanine and dehydrophenylalanine peptides

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 …

CCDC 1035539: Experimental Crystal Structure Determination

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CCDC 298540: Experimental Crystal Structure Determination

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CCDC 619860: Experimental Crystal Structure Determination

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CCDC 604222: Experimental Crystal Structure Determination

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CCDC 934573: Experimental Crystal Structure Determination

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CCDC 160007: Experimental Crystal Structure Determination

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CCDC 774082: Experimental Crystal Structure Determination

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CCDC 934574: Experimental Crystal Structure Determination

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CCDC 934572: Experimental Crystal Structure Determination

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CCDC 619859: Experimental Crystal Structure Determination

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CCDC 619858: Experimental Crystal Structure Determination

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CCDC 633908: Experimental Crystal Structure Determination

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CCDC 278557: Experimental Crystal Structure Determination

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CCDC 647704: Experimental Crystal Structure Determination

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CCDC 1034604: Experimental Crystal Structure Determination

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CCDC 774083: Experimental Crystal Structure Determination

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