USE OF SULFENYL HALIDES IN CARBOHYDRATE REACTIONS .2. USE OF THE METHYLSULFENYL CATION AS AN ACTIVATOR FOR GLYCOSYLATION REACTIONS WITH ALKYL (ARYL) 1-THIOGLYCOPYRANOSIDES - SYNTHESIS OF METHYL O-(2-ACETAMIDO-2-DEOXY-BETA-D-GLUCOPYRANOSYL)-(1-]6)-O-ALPHA-D-GLUCOPYRANOSYL-(1-]2)-ALPHA-D-GLUCOPYRANOSIDE, A DERIVATIVE OF THE CORE TRISACCHARIDE OF ESCHERICHIA-COLI K12

Methylsulfenyl bromide (MSB) and methylsulfenyl trifluoromethanesulfonate (MST) have been used to prepare 1,2-cis-linked disaccharides. Ethyl (phenyl) l-thio-β-d-gluco- and galacto-pyranosides having non-participating (benzyloxy) protecting groups were used as the donors. The αβ-ratio of the products depended on the promoter and conditions of reaction. Intimate ion-pairs, formed initially, may be responsible for the steric outcome of the glycosylations. Thus, with ethyl 2,3,4,6-tetra-O-benzyl-α-d-mannopyranoside as a donor, moderate quantities of the β-linked disaccharide could be produced using MSB as the activator. The synthesis of the title trisaccharide glycoside that contains 1,2-cis and 1,2-trans-linkages is described. © 1990.