Acetic acid (2R,3R,4S,5R,6R)-5-((2R,3R,4S,5R,6R)-5-acetoxy-6-acetoxymethyl-3-allyloxy-4-benzyloxy-tetrahydro-pyran-2-yloxy)-2-acetoxymethyl-4-benzyloxy-6-(2-trimethylsilanyl-ethoxy)-tetrahydro-pyran-3-yl ester