The first total synthesis of hamigerans D, G, L, and N-Q has been accomplished. Aconvergent approachwas used to build the basic tricarbocyclic ring system bearing a5 -6-6 structure.Asequence of oxidative cleavage,homologation, and ring regeneration provided access to the 5-7-6 skeleton of hamigeran G. Based on the biogenetic hypothesis,elegant and highly efficient biomimetic transformations of hamigeran G into hamigerans D, N-Q, and Lw ere achieved. Scheme 4. Total synthesis of 6.X-ray structures are shown. Thermal ellipsoidss hown at 50 %probability. [24] DMP = Dess-Martin periodinane, NMO = 4-methyl-morpholin-4-oxide, PTSA = p-toluenesulfonic acid, Py = pyridine.Scheme 5. Biomimetic transformation of 6 into 8 and its 18-epi isomer.