Dehydrooligopeptides. V. Synthesis of N-carboxy .ALPHA.-dehydroamino acid anhydrides and their transformation to .ALPHA.-dehydroamino acid and dehydrooligopeptide derivatives.
The synthesis of N-carboxy α-dehydroamino acid anhydrides (ΔNCA) from benzyloxycarbonyl-α-dehydroamino acids and the subsequent conversion of these products into new α-dehydroamino acid and dehydrooligopeptide derivatives are described. It was found that the new ΔNCA derivatives were very useful synthons for dehydropeptides. The racemization behavior and configurational determination of all the new dehydrooligopeptides thus obtained are discussed.
dehydrodipeptides with a hydroxyl group, obtained by the coupling of 1 with a serine or threonine ester, and that of N-protected serine or threonine with 2, followed by mesylation and subsequent base-catalyzedβ-elimination gave a number of 7 substances in good yields. The configurational structures of 7 obtained by both direct condensation and elimination were found to have (Z,Z)-geometry.
Dehydrooligopeptides. III. Synthesis of (<i>Z</i>,<i>Z</i>)- and (<i>Z</i>,<i>E</i>)-Geometric Isomers of Dehydrodipeptides and Their Base-catalyzed Transformation to the Hydantoin Derivatives
N-Benzyloxycarbonyl (Cbz)-(Z,E)-dehydrodipeptides, comprised of both (Z)- and (E)-α-dehydroamino acid residues, were first synthesized by dehydrochlorination of Cbz-(Z)-dehydrodipeptides containing an erythro-3-chloro-2-aminobutanoate moiety. Base-catalyzed transformation of the individual Cbz-(Z, Z)- and (Z, E)-dehydrodipeptides was carried out to give the corresponding new hydantoin derivatives.