Since cyclic peptides constitute a group of natural and synthetic products of considerable practical and theoretical significance, model experiments were carried out to explore the scope of the four component condensation for the synthesis of these structures.

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Aus dem Vergleich der chemischen Verschiebungen von den in 2-endo-Stellung substituierten Verbindungen relativ zu den entsprechenden unsubstituierten Vertretern 1, 2 und 3 geht hervor, dass durch die 2-endo-Substitution generell grosse Anderungen in der chemischen Verschiebung von 3-endo-H verursacht werden (Tabelle 1 und 2).

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Since modified peptides embodyinga 1, I-disubstituted hydrazide (11) have not been described previously, model experiments were carried out to determine suitable reaction conditions for their preparation. The synthesis of model compounds of type I1 is the subject of this paper.On a effectue des experiences modeles afin de determiner les conditions de reaction appropriees pour lapreparation de peptides modifies contenant une hydrazide disubstituee en 1,l. La synthkse decomposCs modeles de type I1 fait I'objet de la prtsente publication.[Traduit par le journal]Can.