Structures and Anatomical Distribution of Oxygenated Diterpenes in the Australian Nudibranch Chromodoris reticulata

The structures and stereochemistry of six new diterpenes (1–6), two of which contain cyclic imine functionality, have been deduced by 2D NMR spectroscopy. The anatomical distribution of these, and of 17 other diterpenes (7–23) that were also isolated, has been investigated. The known compound aplyroseol-2 (14) was the major compound in the mantle tissue along with some dialdehydes, while the linear furan ambliofuran (7) was the only diterpene found solely in the internal organs. The presence of lactone-acetal-hemiacetal functionality in many of the isolated compounds is a consequence of the reactive dialdehydes present in the mollusc.