(R)-3-{(E)-(2R,3S)-5-[(2R,4R,5R)-5-Allyl-2-[4-(tert-butyl-dimethyl-silanyloxy)-phenyl]-4-(2-trityloxy-ethyl)-[1,3]dioxolan-4-yl]-2-ethyl-3-triethylsilanyloxy-pent-4-enoyl}-4-benzyl-oxazolidin-2-one