A stereoselective synthesis of a dimer, b-D-Fruf-(2->2)-a-D-Galp-(1-PO3H-3)-[b-D-Fruf-(2->2)]-D-Galp, of the repeating unit of the K52 type CPS of E. coli is described. The b-fructofuranosyl residue was introduced in a DMTST-promoted coupling using a 1,4-TIPS-bridged thiofructofuranoside donor and a 2-OH TMSE galactoside acceptor affording exclusively the b-linked disaccharide. Protecting group manipulation of this disaccharide yielded both a 3-OH acceptor and a reducing disaccharide, which were linked via a phosphate diester bridge using H-phosphonate chem. The hemiacetal is present only as the a-anomer, why phosphorylation yielded stereoselectively the a-H-phosphonate monoester. Activation of the latter with pivaloyl chloride in the presence of the 3-OH disaccharide acceptor and subsequent I2-oxidn. gave the target dimer in good yield. [on SciFinder (R)]