Relative and absolute stereochemistry of diacarperoxides: antimalarial norditerpene endoperoxides from marine sponge Diacarnus megaspinorhabdosa

Five new norditerpene endoperoxides, named diacarperoxides H-L (1-5), and a new norditerpene diol, called diacardiol B (6), were isolated from the South China Sea sponge, Diacarnus megaspinorhabdosa. Their structures, including conformations and absolute configurations, were determined by using spectroscopic analyses, computational approaches and chemical degradation. Diacarperoxides H-J (1-3) showed some interesting stereochemical issues, as well as antimalarial activity.