Total Synthesis of Bioactive Marine Terpenoids

This paper presents the total synthesis of bioactive marine terpenoids as conducted at this laboratory. The syntheses of marine sesquiterpenoid upial and marine diterpenoid sanadaol were conducted from D-mannitol via sequential Michael reaction and fragmentation reaction. The marine diterpenoid fuscol, its related compound, and phomactin D were obtained by sequential Michael reaction and oxidative cleavage of carbon–carbon double bond. The marine diterpenoid claenone was produced by sequential Michael reaction and retro-aldol reaction. Synthesis of the marine diterpenoid (+)-mayolide A involved the stereoselective introduction of a C2-unit and repeated Claisen rearrangement to construct the side chain as key steps. Synthesis of the marine diterpenoid (+)-halimedatrial involved stereoselective formation of the cyclopropane moiety and formation of the diformylcyclopentane moiety as crucial steps. The marine sesterterpenoid dysidiolide was synthesized by intramolecular Diels–Alder reaction as the key step to obtain the decalin moiety.