Two branched-chain deoxy sugars, methyl 5, 6-O-cyclohexylidene-3-deoxy-2-C-methyl-β-D- arabino-hexofuranoside and its α-D-ribo isomer, were easily prepared by the one-step reaction of methyl 5, 6-O-cyclohexylidene-3-O-mesyl-β-D-allofuranoside (3a) with methylmagnesium iodide. Similarly, the corresponding α-mesylate (4a) gave methyl 5, 6-O- cyclohexylidene-3-deoxy-2-C-methyl-α-D-ribo-hexofuranoside. It was demonstrated that ...