9-(tert-butyl-dimethyl-silanyloxy)-4-[4-(tert-butyl-dimethyl-silanyloxy)-1-(3,4-dimethoxy-benzyloxy)-3-methoxy-non-7-ynyl]-2-methoxy-7-[3-methoxy-2-(4-methoxy-benzyloxy)-propyl]-2,8,10-trimethyl-1,3,6-trioxa-spiro[4.5]decane