The azidonitration of tri-<i>O</i>-acetyl-<scp>D</scp>-galactal

Reaction of 3,4,6-tri-O-acetyl-D-galactal with excess ceric ammonium nitrate and sodium azide in acetonitrile produced 2-azido-1-nitrate addition products (53% β-galacto, 22% α-galacto, and 8% α-talo) and N-acetyl-3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranosylamine was formed, on hydrolysis, in 10% yield. The reaction product provides a convenient source of D-galactosamine and 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-D-galactopyranosylhalides. The crystalline β-chloride is also reported. The use of these glycosyl halides as reactants for the preparation of 2-azido-2-deoxy-α- and -β-D-galactopyranosides under conditions promoted by both mercuric cyanide and silver salts are reported.