{(2R,3R,4S)-2-[3-((2R,4aS,6R,7S,8S,8aS)-7,8-Bis-benzyloxy-6-benzyloxymethyl-octahydro-pyrano[3,2-b]pyran-2-yl)-prop-2-ynyl]-4-chloro-tetrahydro-pyran-3-yloxy}-tert-butyl-dimethyl-silane