Synthesis and characterization of 2- O-β-lactosylglycerol, 1,2-di- O-β-lactosyl-( R,S)-glycerols, and 1,2,3-tri- O-β-lactosylglycerol

Abstract

The reaction of 2,3,6,2′,3′,4′,6′-hepta- O-acetyl-α-lactosyl bromide ( 5) and 1,3-di- O-benzylglycerol in the presence of mercury(II) cyanide in benzene-nitromethane afforded 1,3-di- O-benzyl-2- O-(2,3,6,2′,3′,4′, 6′-hepta- O-acetyl-β-lactosyl)glycerol (70%), which was converted into 2- O-β-lactosylglycerol. 1,2-Di- O-β-lactosyl-( R,S)- glycerols were obtained by way of the coupling of 5 to either 1- O-benzyl-( R,S)-glycerol or 1- O-benzyl-2- O-(2,3,6,2′,3′,4′,6′-hepta- O-acetyl-β-lactosyl)-( R,S)-glycerols. The most efficient route to 1,2, 3-tri- O-β-lactosylglycerol ( 17) involved treatment of 2- O-(2,3,6,2′,3′,4′,6′-hepta- O-acetyl-β-lactosyl)glycerol with 3 mol. equiv. of 5 followed by removal of the blocking groups, to give 17 (47%).