Cyclic oligopeptides synthesis

Fig. 6.15. Carboxylic acid activation with DCC. [1,3] means the intramolecular substitution of the oxygen atom 01 by the N atom "3" via a cyclic four-membered tetrahedral intermediate. From the point of view of the heteroatoms, this SN reaction corresponds to a migration of the acyl group R-C=0 from the oxygen to the nitrogen. (Examples for amino acid activations in the form of the pentafluorophenyl ester C or the benzotriazolyl ester D are given in Figure 6.32 (oligopeptide synthesis) and Figure 6.31 (dipeptide synthesis), respectively.

Alternative chemical strategies for the synthesis of nanomaterials, like the organization in the critical region, also rely on self-assembly of suitable monomers. Cyclic oligopeptides may, for instance, be synthesized by linking eight amino acid residues by covalent bonds. The resulting macrocycles self-assemble into nanoscaled tube-like arrays. 

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