The transformation of D-xylose and L-arabinose, the two major components of wheat straw and bran, into a unique multifunctional, optically pure, five-carbon synthon has been achieved. The synthetic sequence requires three steps: suitable protection of the hydroxyl groups of the pentoses, introduction of an iodide at the C-5 position and zinc-mediated opening of the furanose ring leading to the formation of a common substituted pent-4-enal.