3-[(2S,3R,4R,5R,6R)-6-Azidomethyl-4-(tert-butyl-dimethyl-silanyloxy)-3-(1,3-dioxo-1,3-dihydro-isoindol-2-yl)-5-(4-methoxy-benzyloxy)-tetrahydro-pyran-2-ylsulfanyl]-propionic acid