The first total synthesis of optically active coraxeniolide-A (la) and 4-ep
i-coraxeniolide-A (1b) is described. The approach is highly stereoselective
and flexible in the preparation of a wide variety of members of the xeniol
ide family. The use of the Grob-fragmentation was pivotal for the stereospe
cific elaboration of the nine-membered ring. Coraxeniolide-A (la) was synth
esized in 28 steps by using the Hajos-Parrish diketone 2 as starting materi
al which is available enantiomerically pure.