One-step synthesis of β-C-glycosidic ketones in aqueous media : The case of 2-acetamido sugars

The one step synthesis of β-D-C-glycosidic ketones by condensation of pentane-2,4-dione with unprotected N-acetyl-D-gluco-, manno-, and galactosamine in alkaline aqueous media has been explored. N-Acetyl-D-gluco- and mannosamine gave, in good yield, a mixture of the two gluco and manno C-glycosidic ketones, which were separated by crystallization after acetylation, whereas N-acetyl-D-galactosamine afforded the galacto C-glycosidic ketone which was isolated as its acetylated derivative in 50% yield.