4-{4-[7-(tert-butyl-dimethyl-silanyloxymethyl)-4-hydroxy-2-methoxy-5-methyl-non-5-enyl]-10-methoxy-5,5-dimethyl-2-naphthalen-2-yl-11-triethylsilanyloxy-1,3,7-trioxa-spiro[5.5]undec-8-yl}-3-methoxy-2-methoxymethoxy-butyric acid methyl ester