Total synthesis of (±)-dysidiolide

The total synthesis of (±)-dysidiolide was accomplished with a high level of intramolecular stereo-induction. Methylation of 6-carboethoxy-3-chloro-5-methyl-cyclohex-2-enone provided bearing the 6,7-trans-dimethyl substitution of the C6–C11 B-ring. Diastereoselective conjugate addition upon enone installed the C11 stereogenic center. Annulation then provided an A-ring enone (), a substrate for a challenging conjugate addition of the branched pentenyl side chain. The combination of tri-n-butylphosphine, boron trifluoride etherate, and a dialkylcuprate uniquely effected conjugate addition to yield . Incorporation of the hydroxybutenolide-containing side chain completed the total synthesis and established the viability of a general approach for the preparation of the isolabdanoid terpene system.