Cumulated Ylides XX. Syntheses of (E)-α,β-Unsaturated Macrocyclic Lactones by Intramolecular Wittig-Olefination via Triphenylphosphoranylideneketene

Article abstract of DOI:10.1055/s-1989-27271

Two methods for closure of macrocyclic lactone rings by intramolecular Wittig reaction of (ω-oxoalkoxy)carbonylmethylenetriphenylphosphoranes are described.The latter are easily accessible by addition of the appropriate (free or protected) ω-hydroxyalkanals to the cumulated ylide triphenylphosphoranylideneketene.Examples are then given for the use of these methods in natural product synthesis.