Access to Resorcylic Acid Lactones <i>via</i> Phosphonate Based Intramolecular Olefination

An approach to resorcylic acid lactones is described, exploiting an intramolecular olefination reaction for the generation of the 14-membered macrolactone. The synthetic route gave zearalenone precursors, and the preparations of other RAL analogues, trans- and cis-resorcylides are included, the latter being prepared by photoisomerization of the trans-isomer. β-Haloketone derivatives were also prepared in a highly stereoselective manner by conjugate addition of chloride or bromide to the E-enone using boron trichloride and boron tribromide, respectively.