(-)-tert-butyl ((3'aS,4'R,5'R,6'aR)-4'-((3S,4S,E)-3-(tert-butyldimethylsilyloxy)-4-methyloct-1-en-6-ynyl)-5,5-dimethylhexahydro-1'H-spiro[[1,3]-dioxane-2,2'-pentalene]-5'-yloxy)dimethylsilane