The cyclocinamides possess a unique β2αβ2α 14-membered tetrapeptide core. The initially reported biological data and intriguing structure, which was without full stereochemical identification, necessitated synthesis of both nominal (all S) cyclocinamide A and the 11R isomer. The completed synthesis is highlighted by the use of a (cyclo)asparagine-containing dipeptide as a turn inducing fragment. Due to inconsistencies in analytical data between natural and synthetic samples, a re-evaluation of the natural product stereochemistry appears necessary.

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The total synthesis of nominal cyclocinamide B, a cyclic peptide marine natural product, is reported together with an isomer of nominal cyclocinamide A. Initial attempts at the synthesis of the title compounds by inclusion of a turn inducer failed. However, direct synthesis succeeded in formation of the 14-membered cyclic peptide structure. Comparison of the data from all synthetic cyclocinamide A and B compounds with those of the natural products leads to the conclusion that the two natural products possess the same relative stereochemistry and that the true structures have not been defined.

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