{(2R,3S)-3-[(1S,3R)-3-Benzyloxy-3-((2S,3R,5S,6R)-5-benzyloxy-6-benzyloxymethyl-2-methyl-3-triisopropylsilanyloxy-tetrahydro-pyran-2-yl)-1-phenylselanyl-propoxy]-tetrahydro-pyran-2-yl}-methanol