Convergent Route to the Spirohexenolide Macrocycle

Using key functional dissections, the synthesis of spirohexenolides is examined through a three-component strategy that features a 1,2-addition to couple tetronate and aldehyde components forming the C2−C3 bond and a Stille coupling to install the third sulfone-containing component. The macrocycle is completed by an intramolecular Julia−Kocienski reaction to form the C10−C11 trans-disubstituted olefin. Application of this strategy is described in progress toward the synthesis of (±)-spirohexenolide B.