Total Synthesis Of Clavulactone

Clavulactone(1-38), one of dolabellane diterpenoids and isolated by Wu andcoworkers from soft coral Clavularia Viridis in1987, has a unique trans-bicyclo [9.3.0]tetradecan framework. This structure attracted much attention for its total synthesis.Our efforts toward the total synthesis of Clavulactone were disclosed in this thesis.In the first part (chapter2.3), a reliable and efficient method was explored toconstruct the aldehyde2-31, a key intermidate which have the desired quaternarycarbon and a proper level of functionalization on the five-membered ring. The keystep in the synthesis was desymmetritization by Michael addition.In the second part (chapter2.4), the first strategy of construction of theseven-member ring was attempted. After intensive investigation, compound2-51wasobtained. However, its cyclization by RCM was unsuccessful. So the compound2-53was obtained further, and its cyclization by RCM gave our desired structure. Afterremoving the benzyl group of compound2-55, the compound2-56was gainedsuccessfully.In the third part (chapter2.5and2.6), the second strategy was attempted toconstruct a segment based on the second part. Then we motifs the five-member cyclebased on the first part. With the two segments in hand, however, the followingattempts for couple them by the Nozaki-Hiyama-Kishi reaction was unsuccessful.Further investigation is still in progress in this laboratory.