2-Deoxy-2,3-dehydro-N-acetylneuraminic acid 24967-27-9 D-glycero-D-galacto-Non-2-enonic acid, 5-(acetylamino)-2,6-anhydro-3,5-dideoxy- DANA EINECS 246-550-7 N-Acetyl-2,3-didehydro-2-deoxyneuraminic acid