A short synthesis of the anti-leukemic sesquiterpene (+)-caparratriene employing aqueous Wittig chemistry

An efficient, stereoselective method for the synthesis of (+)-caparratriene based on an aqueous Wittig reaction has been developed. A functionalized triethylallyl ylide reacted under various conditions with (+)-citronellal to deliver (+)-caparratriene in only three steps with excellent overall yield. The Wittig reaction proceeded with exclusive (4E)-selectivity and an interesting cationic effect was uncovered with good stereoselectivity at the isomerizable allylic position being observed in the presence of lithium salts.