Homonuclear 2D 1H,1H COSY and 1H,1H TOCSY experiments showed connectivity of this proton to one and two other protons, respectively (Fig. S2). Signal 2, at 2.73 ppm, corresponds then to a proton neighboring a carbonyl on one side and at least two other protons on the other side with chemical shifts in the 3-4 ppm region. If you have any questions regarding where and ways to utilize sialic acid manufacturers, you can contact us at our website. Analysis of the 3-4 ppm spectral region, where standard sugar-ring C-H signals typically show, suggests that the intermediate chemical shifts are closer to Neu5Ac than to 2,7-anhydro-Neu5Ac (Fig. S3).