A -Acetyl-o-galactosamine

Using optimized conditions (pentanedione 2 equiv., NaHCOs 4 equiv., H2O-THF 2 1, 90°C, 24 h), Ai-acetyl-o-glucosamine (66) gave the gluco- and manno ketones 69a and 70a in a 4 6 ratio and 83% yield, whereas Af-acetyl-o-mannosa-mine (67) led to the same products in a 3 1 ratio and 40% yield. This poor yield has been explained by the instability of 70a in the reaction mixture. These compounds were easily separated by crystallization of their acetylated derivatives 69b and 70b. Applied to A-acetyl-D-galactosamine (68), the same reaction conditions gave the C-glycosidic ketone 71a, isolated as the acetylated compound 71b (Fig. 12, Table 4). 

O Figure 15 presents the structures of the three most important and abundant hexosamines found in nature fV-acetyl-D-glucosamine, A-acetyl-D-galactosamine, and IV-acetyl-D-man-nosamine. 

So-called jS-heparin, an anticoagulant isolated from the lung (55) is probably chondroitin sulfate B, for it contains approximately equimolar quantities of A-acetyl-D-galactosamine, a uronic acid (n-iduronic acid- ) and sulfuric acid (14a)- It has about one-third of the anticoagulant activity of the usual heparin ( a-heparin O-... 

T.P. Skelton, L.V, Hooper, V. Srivastava, O. Hindsgaul and J.U. Baenziger, Characterization of a sulfotransferase responsible for the 4-O-sulfation of terminal p-A-acetyl-D-galactosamine on asparagine-linked oligosaccharides of glycoprotein hormones. J. Biol Chem., 1991, 266, 17142-17150. 

Nitroglycals65 are excellent Michael-type acceptors,66 where O-, N-, S-, C- and P-nucleophiles can be used as donors.67 An application of this kind of reaction was reported by Schmidt et al. for a new synthesis of 2-deoxy-2-nitro-D-galactose nucleoside 86 and of /V-acetyl-D-galactosamine nucleoside 88, based on addition reactions to 3,4,6-tri-0-benzyl-2-nitro-D-galactal 85 (Scheme 28).68... 

Tsuruta, O, Shinohara, G, Yuasa, H, Hashimoto, H, UDP-A-acetyl-5-thio-galactosamine is a substrate of lactose S3mthase, Bioorg. Med. Chem. Lett., 1, 2523-2526, 1997. 

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