Compound 54 is then converted in two steps into O-(2,3,4-tri-O-acetyl-6-chloro-6-deoxy-α-D-glucopyranosyl) trichloroacetimidate (55). First, the anomeric acetate group of compound 54 is selectively removed by reaction with hydrazine acetate. Preferably, this reaction is conducted by contacting compound 54 with from about 1.1 to about 1.5 equivalents of hydrazine acetate (prepared by known procedures from hydrazine and acetic anhydride) at a temperature of from about 0° C. to about 20° C. for about 5 to about 10 hours. Typically, the reaction is conducted in an anhydrous solvent, such as dimethylformamide. Treatment of the resulting product with trichloroacetonitrile in the presence of an amine, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), provides compound 55. This reaction is typically conducted in an anhydrous inert organic solvent, such as dichloromethane, using an excess of trichloroacetonitrile.
