Acetic acid (2R,3S,4S,5R,6S)-3,5-diacetoxy-2-acetoxymethyl-6-((2S,3R,4R,5S,6S)-4,5-diacetoxy-6-bromo-2-methyl-tetrahydro-pyran-3-yloxy)-tetrahydro-pyran-4-yl ester