2-O-Methyl-d-erythrose, 2-O-methyl-l-threose, 2-deoxy-d-and l-erythrose, and the corresponding acetonides have been prepared from the commercially available d- isoascorbic and l-ascorbic acids. The proportion of cyclic (α and β furanoses) and acyclic (aldehyde and hydrate) forms was determined in aqueous (D2O) solution by 1H and 13C NMR spectroscopy.