ABSTRACT
2-Acetamido-1,3,4,6-tetra-O-acetyl-2-deoxy-β-d-glucopyranose 2 is a starting compound in the synthesis of a number of glucosamine glycosyl donors, such as 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranosyl chloride, 1,2 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)-[2,1-d]-2-oxazoline, 3,4 as well as thioglycoside derivatives of N-acetyl-d-glucosamine. 5 It was shown 4–7 that in the presence of excess of anhydrous ferric chloride in dichloromethane, the glycosyl acetate 2 easily reacted with simple alkyl and carbohydrate alcohols to give stereoselectively the corresponding 1,2-trans glycosides. Recently, a milder glycosylation procedure was proposed 8,9 where the glycosyl donor 2 was used in the presence of catalytic amounts of ferric triflate or ferric triflate—dimethyl sulfoxide complex and excess of 2,4,6-tri-tert-butylpyrimidine. Despite its moderate reactivity, glycosyl donor 2 is useful because it affords glycosides and oligosaccharides with natural 2-acetamido group.
