PRACTICAL SYNTHESIS OF O-β-D-MANNOPYRANOSYL-, O-α-D-MANNOPYRANOSYL-, AND O-β-D-GLUCOPYRANOSYL-(1->4)-O-α-L-RHAMNOPYRANOSYL-(1->3)-D-GALACTOSES

Article abstract of DOI:10.1016/S0008-6215(00)85552-4

The Koenigs-Knorr glycosylation of 4,6-O-ethylidene-1,2-O-isopropylidene-3-O-(2,3-O-isopropylidene-α-L-rhamnopyranosyl)-α-D-galactopyranose (3) by 4,6-di-O-acetyl-2,3-O-carbonyl-α-D-mannopyranosyl bromide (10), as well as Helferich glycosylations of 3 by tetra-O-acetyl-α-D-mannopyranosyl and -α-D-glucopyranosyl bromides, proceeded smoothly to give high yields of trisaccharide derivatives (12, 16, and 17).An efficient procedure for the transformation of 12, 16, and 17 into the α-deca-acetates of the respective trisaccharides has been developed.Zemplen deacetylation then afforded the title trisaccharides in yields of 53, 52, and 62percent respectively, from 3.A new route to 1,4,6-tri-O-acetyl-2,3-O-carbonyl-α-D-mannopyranose is suggested.