(2S,4S,7R)-1-{2-[(2S,4S)-6-Benzyloxy-2,4-bis-(tert-butyl-diphenyl-silanyloxy)-hexyl]-[1,3]dithian-2-yl}-2-methyl-7-((2S,3R)-3-methyl-1,5-dioxa-spiro[5.5]undec-2-yl)-6-methylene-octane-2,4-diol