To a solution of N-(5-iodopyridin-2-yl)-4-methylbenzenesulfonamide (33.1 g) in DMF (400 ml) was added NaH (40% oil dispersion, 3.89 g) at 0° C., and the mixture was stirred at room temperature for 30 min. Then 2-bromo-1-cyclopropylpropan-1-one (23.5 g) was added, and the resulting mixture was stirred at room temperature overnight. The mixture was poured into water, and extracted with EtOAc. The extract was washed with brine, dried over MgSO4, and concentrated. The resulting solid was suspended in IPE, stirred for 1 h, and collected by filtration. The crude product was dissolved in EtOAc (1100 ml) at 70° C., and hexane (400 ml) was added while the temperature was maintained at 60° C. Seed crystal was added, and the mixture was stirred at the same temperature for 1 h. Additional hexane (400 ml) was added at 60° C., and the mixture was allowed to cool to room temperature overnight. The precipitate was collected by filtration, washed with hexane/EtOAc (1/1) 3 times, and dried to give the title compound (30.5 g) as a white solid.
