4,19-Dioxabicyclo[13.3.1]nonadec-12-en-3-one,5-(4-bromophenyl)-1,17-dihydroxy-10,11,18-trimethoxy-2,14,16-trimethyl-, (1R,2S,5S,10S,11R,12E,14S,15S,16S,17S,18R)-