(1S,2R,3S,4S)-2-(tert-Butyl-dimethyl-silanyloxy)-1-{(2S,5R)-5-[2-(tert-butyl-dimethyl-silanyloxy)-1,1-dimethyl-ethyl]-2-methyl-tetrahydro-furan-2-yl}-4-methyl-hept-6-ene-1,3-diol