Facile Synthesis of per-O-tert-Butyldimethylsilyl-β-D-galactofuranose and Efficient Glycosylation via the Galactofuranosyl Iodide

The synthesis of crystalline per-O-TBS-beta-D-galactofuranose (4 beta) as a new precursor of D-Galf units is described. Anomeric iodination by reaction with TMSI followed by in situ coupling with simple alcohols and a wide variety of glycosyl acceptors, in the absence of a promoter, was employed as a new efficient glycosylation method for the assembly Of D-galactofuranosyl moieties with high beta-stereoselectivity. Under the mild conditions of this reaction labile protective groups, like acetals, and furanosyl linkages are preserved.