Strophiofimbrins A and B: Two Rearranged Norditerpenoids with Novel Tricyclic Carbon Skeletons from .

Two rearranged norditerpenoids with novel tricyclic carbon skeletons, strophiofimbrin A () and strophiofimbrin B (), were isolated from . Their structures were established by 1D/2D NMR spectroscopy, HRESIMS, quantum chemistry calculations, and X-ray diffraction analyses. and represented the first examples of diterpenoids with unprecedented 5/6/7-fused ring systems.