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DOI: 10.1055/s-0033-1340400
Cyclic Peptide Synthesis Using Peptidyl Salicylaldehyde Esters
Publication History
Publication Date:
13 December 2013 (online)
![](https://www.thieme-connect.de/media/synfacts/201401/i_y141_s1_10-1055_s-0033-1340400.gif)
Significance
A protocol for the solid-phase synthesis of cyclopeptides was described. Starting from MBHA resin and 1, peptide 3 was prepared in 50–90% purity utilizing Boc-SPPS. Ozonolysis of 3 afforded a salicylaldehyde ester peptide 4 in 55% yield (other 15 examples: 42–89% yield). The reaction of 4 in the mixture of pyridine, acetic acid and 2,2,2-trifluoroethanol (1:1:2) followed by TFA treatment gave mahafacyclin B in 56% yield over two steps (other 7 examples: 29–65% yield).
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Comment
The present cyclization of salicylaldehyde ester peptides bearing a Thr or Ser N-terminal residue (5) proceeds via the formation of salicylidene N,O-acetals 6. Li’s group reported a similar approach on the cyclic peptide synthesis independently (C. T. T. Wong et al. Angew. Chem. Int. Ed. 2013, 52, 10212).
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![](https://www.thieme-connect.de/media/synfacts/201401/i_y141_s1_10-1055_s-0033-1340400.gif)