Sinucrassins A—K, Casbane‐type Diterpenoids from the South China Sea Soft Coral Sinularia crassa

Main observation and conclusion A detailed chemical study on the Hainan soft coral Sinularia crass has resulted in the isolation and characterization of eleven casbane‐type diterpenoids, named sinucrassins A—K (1—11), along with six known related ones (12—17). Their structures were elucidated by extensive spectroscopic analyses and comparison with the reported data. The absolute configurations of new compounds were determined by the X‐ray diffraction analysis and computer‐assisted structural elucidation including 13 C NMR data calculation and time‐dependent density functional theory/electronic circular dichroism calculation.