The preparation of heptulopyranosyl donors 13-15, 28, 29 and 3-octulop
yranosyl donors 34, 35, having a non-participating group at C-3 or C-4
, respectively, is described. Glycosylations of various accepters with
these donors gave exclusively cc-linked ketosides. On the other hand,
condensation of 3-O-benzoyl heptulopyranosyl donor 19 with art accept
or furnished an anomeric mixture of ketodisaccharides.