Stemodinone, synthesis

Two different syntheses of aphidicolin (106) were reported in 1979. Corey and his co-workers have now completed a third.A key feature of their route is the base-induced conversion of (104) to (105). It was found that the desired alkylation occurred only under carefully controlled reaction conditions (lithium di-t-butylamide at —102 C), the alternative a-alkylation product predominating under most other conditions. A closely related approach has resulted in the synthesis of ( )-stemodin (107) and ( )-stemodinone (108). The Kametani route to the aphidocolanes has been described earlier in this chapter. 

---