Stereoselective synthesis of methyl 4,6-O-benzylidene-2-C-methoxycarbonylmethyl-α-d-ribo-hexopyranosid-3-ulose, and its X-ray crystallographic analysis

Methyl 4,6-O-benzylidene-2-C-methoxycarbonylmethyl-α-d-ribo-hexopyranosid-3-ulose has been stereoselectively synthesized in 65% yield by reaction of methyl 4,6-O-benzylidene-α-d-arabino-hexopyranosid-2-ulose with diethyl malonate. X-ray crystallographic structure analysis reveals that the chain-branch and the OH group are bonded to C-2 in axial and equatorial positions, respectively. The molecules in the crystal lattice are stacked along a one-dimensional chain, with intermolecular hydrogen bonds between O-8 of one molecule and 2-OH of the next as well as intramolecular hydrogen bonds between O-3 and 2-OH. All phenyl groups are parallel as well as the planes of sugar rings in the molecular columnar stacking.