Stereoselective Synthesis of 2-C-Acetonyl-2-Deoxy-D-Galactosides using 1,2-Cyclopropaneacetylated Sugar as Novel Glycosyl Donor

1,2-Cyclopropaneacetylated sugar is an effective glycosyl donor, which reacted with various glycosyl acceptors including monosaccharides, amino acids and other alcohols in the presence of BF3 center dot OEt2 or TMSOTf. The glycosylation is stereoselective in favor of beta-anomeric products with BF3 center dot OEt2 as catalyst, whereas TMSOTf-catalyzed glycosylation prefers the alpha-anomeric products. 2-C-Acetonyl-2-deoxy-D-galactosides were obtained in good yields.