Synthesis of (+)-Dihydro- epi -deoxyarteannuin B

The synthesis of (+)-dihydro-epi-deoxyarteannuin B (3) from (-)-isopulegol is described. Difficulties in the alkylation of menthone derivatives (e.g., 4a --> 6a) were overcome by using Noyori's zincate enolate method. Related problems with nucleophilic addition to the hindered menthone core of 6a were resolved by using either organocerium or acetylide nucleophiles. Finally, two alternative olefin metathesis approaches are reported for the final cyclization. This study provides insight into the reactivity and synthetic processing of the artemisinin sesquiterpenes.