Stellattamide

Reports on new structures include the new alkaloid polycanthisine, isolated from the genus Astragalus [37], and a marine indolizidine alkaloid, stellattamide B, isolated from a Korean sponge. Fig. (20) [38]. 

D NMR studies of stellattamide B allowed the identification of the indolizidine nucleus and of the side chain structure. The relative configuration of the indolizidine nucleus was established by NOESY connectivities and the absolute stereochemistry of the 13 -methyl group was determined via chemical oxidation of the side chain to (S)-2-methylglutaric acid. The nature of the counterion was determined by energy-dispersive spectroscopic experiments. 

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