2-O-Methyl-4,7,8,9-tetra-O-acetyl-N-acetyl-alpha-D-neuraminic acid 50669-91-5 D-glycero-alpha-D-galacto-2-Nonulopyranosidonic acid, methyl 5-(acetylamino)-3,5-dideoxy-, 4,7,8,9-tetraacetate