2,2-Dimethyl-propionic acid (2R,4S,6R)-2-benzyloxymethyl-6-[(2S,6S)-6-(2-methyl-oxazol-4-yl)-4-triethylsilanyloxy-5,6-dihydro-2H-pyran-2-ylmethyl]-tetrahydro-pyran-4-yl ester