(E)-(1R,7S,11S,15S,17R)-7-((E)-(S)-1-Hydroxy-4-methoxy-but-2-enyl)-11-methoxymethoxy-15-methyl-13-methylene-6,21-dioxa-bicyclo[15.3.1]henicosa-9,19-dien-3-yn-5-one