Description
The total syntheses of two peptidic cytotoxins, micromide and lagunamide A was completed employing both solid-phase and solution-phase methods. Micromide was isolated from an unknown species of marine cyanobacterium of the genus Symploca. Its synthesis was accomplished using both solid-phase and solution-phase chemistry. Comparison of the synthetic and natural product’s NMR spectra reveal that the reported structure of micromide was incorrect. Syntheses of multiple analogs of micromide was completed to resolve the discrepancies in the NMR spectra. The new data suggests that micromide requires a structural revision. Lagunamide A is a cyclic depsipeptide also isolated from marine cyanobacteria, originally identified as Lyngbya majuscula. Recent genetic analysis found that a separate cyanobacterium, Moorea procudens, exhibited very similar morphology to L. majuscula and many natural products were mistakenly attributed to L. majuscula. The origin of lagunamide A has not been confirmed after this new revelation. Synthesis of the peptide portion was achieved through solid-phase peptide synthesis (SPPS) and the polyketide moiety was achieved using Kobayashi’s vinylogous Mukaiyama aldol reaction (VMAR).
