Total Synthesis of (+)-Saponaceolide B.

Coupling of three fragments results in the first total synthesis of a saponaceolide (see scheme). The first fragment, the spiroketal portion, is formed from two moieties, one derived from geraniol and the other from allyl malonate. A sulfone alkylation-desulfonylation sequence joins the spiroketal portion to the methylene-3,3-dimethylcyclohexane unit. The subsequent stereoselective Wittig reaction attaches the final piece to complete the synthesis of saponaceolide B (1), one of the most biologically active members of this family.