To a suspension of 1-(2-cyclopropyl-1-methyl-1H-benzimidazol-6-yl)-4-hydroxypyridin-2(1H)-one (2 g) in DMF (35 ml) was added phosphoryltribromide (2.45 g) at room temperature, and the mixture was stirred at 50° C. overnight. The mixture was poured into saturated NaHCO3 solution, and extracted with EtOAc. The organic layer was washed with water and brine successively, dried over MgSO4 and concentrated in vacua. The resulting residual solid was recrystallized from EtOH-hexane to give the title compound (1.70 g) as a brown solid.
