Reaction of equiraolecular amounts of xylose and urea in D2O at 68 °C, monitored by13C NMR, gave a six carbon xylofuranosyl derivative as the major product. No intermediate in the formation of this monomeric compound was detected. The xylofuranosyl derivative was subsequently isolated and purified from a six week 0.1 molar reaction of xylose and urea in H2O. Its structure, α-d-xylo-furano[1,2-d]oxazolidin-2-one1, was confirmed by elemental analysis,1H coupled and decoupled13C NMR,1H NMR, IR and DCI-MS. The1H NMR and GC-MS (El, DCI) of theN-acetyl-di-O-acetyl derivative2were in agreement with structure1.