Structure and absolute configuration of 3-alkylpiperidine alkaloids from an Indonesian sponge of the genus Halichondria

Chemical analysis of an Indonesian sponge sample has provided three new 3-alkylpiperidine alkaloids, tetradehydrohaliclonacyclamine A, its mono-N-oxide derivative, and a 2-epi isomer. The absolute structure of tetradehydrohaliclonacyclamine A has been established by X-ray crystallography from anomalous dispersion effects using Cu radiation, which determined that the absolute configuration is 2S, 3S, 7S, 9S while an HPLC study revealed that the alkaloid is enantiomerically pure.

Graphical abstractThe structure and relative configuration of three new 3-alkylpiperidines, tetradehydrohaliclonacyclamine A 10, its mono-N-oxide 11, and the C-2 epimer 12, have been deduced by 2D NMR spectroscopy. An X-ray crystallographic study has provided the absolute configuration of 10.Figure optionsDownload full-size imageDownload as PowerPoint slide