The condensation reaction of acetobromoglucose with chloromercuri-4-ethoxy-2 (1H)-pyrimidinone (I), which had been reported by Fox, et al. to yield 1-(tetra-O-acetyl-β-D-glucopyranosyl)-4-ethoxy-2 (1H)-pyrimidinone (II), was reinvestigated. It was confirmed that the main product of the reaction is not the N-glucoside (II) but the O-glucoside, 2-[(tetra-O-acetyl-D-glucopyranosyl)oxy]-4-ethoxypyrimidine (III). II was obtained as a minor product of the reaction. The O-glucoside (III) was converted to the N-glucoside (II) by the action of mercuric bromide in boiling xylene in a yield of 30∼40%. This transglycosidation reaction was followed by ultraviolet absorption spectrum and by the yield of II isolated from the reaction mixture. A direct synthesis of II by the condensation of acetobromoglucose with I in the presence of mercuric bromide was described.