Acetic acid (2S,3R,4R,5S,6S)-5-benzyloxy-2-((2R,3R,4R,5S,6S)-4,5-bis-benzyloxy-6-methyl-2-pent-4-enyloxy-tetrahydro-pyran-3-yloxy)-4-(9H-fluoren-9-ylmethoxycarbonyloxy)-6-methyl-tetrahydro-pyran-3-yl ester