D-Glucal triacetate reacted with iodonium and bromonium di-sym-collidine perchlorate complexes in the presence of 2,3,4,6-tetra-O-acetyl-β-D-glucopyranose to yield, after deacetylation, crystalline β-D-glucopyranosyl 2-deoxy-2-halogeno-α-D-mannopyranosides. The halogen was hydrogenolyzed catalytically to yield β-D-glucopyranosyl 2-deoxy-α-D-arabino-hexopyranoside (2-deoxy-neotrehalose) isolated as the crystalline heptaacetate. A correction of the literature is made regarding the preparation of "2,3,4,6-tetra-O-acetyl-α-D-glucopyranose".