Synthesis and spectroscopic characterization of hydroxycinnamoylated methyl α- l-arabinofuranosyl-(1 → 2)- and (1 → 3)-β- d-xylopyranosides

A reaction sequence for the preparation of methyl 5- O-feruloyl-α- l-arabinofuranosyl-(1 → 3)-β- d-xylopyranoside, the companion 5- O- p-coumaroyl disaccharide, and their (1 → 2) analogs has been developed. The (1 → 3) hydroxycinnamoylated disaccharides are available in 11 steps from l-arabinose and methyl β- d-xylopyranoside in 17% overall yield (based on methyl β- d-xylopyranoside). The corresponding (1 → 2) materials were prepared in 9 steps in > 37% overall yield. Complete spectral characterization provides unambiguous assignments for comparison with analogous materials isolated from plant cell-walls. Conformational aspects of the prepared materials are discussed in relation to coupling-constant information.