Convergent Synthesis of Trisubstituted Z-Allylic Esters by Wittig-Schlosser Reaction

beta-Lithiooxyphosphonium ylides, generated in situ from aldehydes and Wittig reagents, react readily with halomethyl esters to form trisubstituted Z-allylic esters. The methodology was applied to a total synthesis of the geranylgeraniol-derived diterpene (6S,7R,Z)-7-hydroxy-2-((E)-6-hydroxy4-methylhex-4-enylidene)-6,10-dimethylundec-9-enyl acetate (12).