An efficient synthesis of the guaiane sesquiterpene (-)-isoguaiene by domino metathesis.

(-)-Isoguaiene was prepared from (S)-citronellal in only 9-10 steps with good overall yields. Either a trienyne or a dienediyne metathesis and highly diastereoselective organocatalytic Michael additions of aldehydes derived from (S)-citronellal served as the key transformations.