Synthesis of 4-O-β-D-Glucopyranosyl-L-rhamnopyranose

4-O-(β-D-Glucopyranosyl)-L-rhamnose (scillabiose) has been synthesized in 55% yield by condensation of 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide with methyl 2,3-O-isopropylidene-α-L-rhamnopyranoside using mercuric cyanide in acetonitrile (Helferich reaction). The disaccharide and the derived alditol are both syrups but each forms a crystalline peracetate. A convenient synthesis of 1-deoxy-D-erythritol is described.