The condensation of 2-(trimethylsilyloxy)-5-iodopyrimidine (II) with the protected sugar chloride (I) by means of SnCl4 in 1,2-dichloroethane gives the pyrimidinone (II), which is finally deprotected by means of NaHCO3 in methylene chloride/water and isolated from a minor amount of the alpha-isomer by crystallization from ethyl acetate.