(E)-(R)-4-[(3aR,4R,7S,7aR)-2,2-Dimethyl-7-((E)-(4R,5S)-4-methyl-5-triisopropylsilanyloxy-hex-2-enyl)-tetrahydro-[1,3]dioxolo[4,5-c]pyran-4-yl]-3-methyl-4-triisopropylsilanyloxy-but-2-enoic acid ethyl ester