(2S,3S,6S,7R,8aR)-5-(((3,4-dimethoxybenzyl)oxy)methyl)-2-((E)-4-iodopent-3-en-1-yl)-2,6,7-trimethyl-3-((triethylsilyl)oxy)-6-vinyl-2,3,6,7,8,8a-hexahydro-4H-chromen-4-one