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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1295-1301 
    ISSN: 0170-2041
    Keywords: 2-Azidocarboxylates ; Rhenium catalysts ; Amino acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amino Acids, 16. - Synthesis of N-Acyl-2,3-didehydro-2-amino Acid Esters[2]N-Acyl-2,3-didehydro-2-amino acid esters 3, 5, 7-12, with a great variety of N-substituents, are obtained in good yields by the perrhenate-catalyzed decomposition of methyl 2-azido carboxylates 1 in organic solvents in the presence of the corresponding acyl chlorides 2. By using methyl 2-azidoisovalerate (1a), the conditions (catalyst, solvent, temperature) for the reaction to give 3a were optimized. The reactivity of acyl chlorides can be strongly enhanced with equimolar amounts of dimethyl formamide, which allows a lowering of the decomposition temperature for this reaction. Under these mild reaction conditions also the unstable N-acyldehydroalanine derivative 5f can be obtained in good yield.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1303-1311 
    ISSN: 0170-2041
    Keywords: 2-Azidocarboxylates ; Rhenium catalysts ; Peptides ; Amino acids ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amino Acids, 17. - A New Synthesis of Didehydro Dipeptides and Didehydro TripeptidesEsters of N-phthaloyl-protected (R)- or (S)-didehydro dipeptides 5-7 were obtained in good yields by the perrhenate-catalyzed decomposition of 2-azidocarboxylates 1 with N-phthaloyl-protected (R)- or (S)-amino acid chlorides 2 in presence of at least equimolar amounts of N-methyl-2-pyridone (4) as acylation catalyst. Esters of didehydro tripeptides 16 were obtained in a comparable procedure from the optically active amino acid chlorides 2 and 2-(2-azidoacyl)amino acid esters 15, which were prepared from 2-azidocarboxylic acids 12 or the corresponding chlorides 13 with 2-amino acid ester hydrochlorides (S)-14. - As an example, the unprotected (S)-alanly-didehydrovalin 20 was prepared from the didehydro dipeptide 18a without any racemization by hydrolysis of the benzyl ester and subsequent hydrogenolytic removal of the N-phthaloyl group.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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