GlyTouCan:G23553KL → 2-deoxy-2-fluoro-4-O-formyl-D-ribose

In step 2, compound (2) obtained in step 1 above is dissolved in acetic acid and oxidized with lead tetra-acetate at room temperature to cause an oxidative cleavage of the α-glycol of 3-deoxy-3-fluoro-D-allopyranose, whereby the 2-carbon atom forms a formyl group. Thus, 2-deoxy-2-fluoro-4-O-formyl-D-ribose is formed as the oxidative product, which is then heated at 70°-90° C. in an aqueous solution under an acidic condition for the elimination of O-formyl group, whereby a ring-closing reaction occurs again to form 2-deoxy-2-fluoro-α,β-D-ribofuranose [compound (3)]. In the next step 3, compound (3) above is reacted with methanol in hydrogen chloride-methanol at room temperature for methylglycosidation, whereby forming a mixture of methyl 2-deoxy-2-fluoro-α-D-ribofuranoside [compound (4)] and methyl 2-deoxy-2-fluoro-β-D-ribofuranoside [compound (5)].