Effective protection of the N-sulfate of glucosamine derivatives with the 2,2,2-trichloroethyl group

The 2,2,2-trichloroethyl (TCE) group was utilized as the first protecting group for N-sulfates (chlorosulfuric acid TCE ester, Et3N, DMAP, DMF). Glycosylation with 3,4,6-tri-O-acetyl-N-trichloroethylsulfuryl-α-d-glucosaminosyl trichloroacetimidate provided the corresponding β-glucosaminosides stereoselectively and in excellent yields. The TCE protection stayed stable under a variety of conditions for the manipulation of other protecting groups, and was readily removable with zinc in the presence of ammonium chloride in methanol.