Stereoselective synthesis of calonectrin

Several macrocyclic lactones of the trichothecene class of compounds exhibit significant anticancer activity.\u27 A common structural subunit in each of these lactones is the sesquiterpene verrucarol(1). Anguidin (2), a more highly oxygenated analogue, also shows inhibitory activity against several cancers., Calonectrin (3), considered to be the biogenetic precursor to verru~arol,~ has recently been isolated