Acetic acid (2R,3R,4R,5R,6S)-3-acetoxy-2-acetoxymethyl-6-((2R,3S,4S,5R)-3,5-bis-benzyloxy-2-benzyloxymethyl-6-fluoro-tetrahydro-pyran-4-yloxy)-5-(1,3-dioxo-1,3-dihydro-isoindol-2-yl)-tetrahydro-pyran-4-yl ester