To a solution of N-(5-iodopyridin-2-yl)-4-methylbenzenesulfonamide (33.1 g) in DMF (400 mL) was added sodium hydride (60% 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 to the obtained mixture, and the mixture was stirred at room temperature overnight. The reaction mixture was poured into water and extracted with ethyl acetate. The obtained organic layer was washed with brine, dried over magnesium sulfate, and concentrated in vacuo. The resulting solid was suspended in diisopropyl ether, the suspension was stirred for 1 hr, and the solid was collected by filtration. The obtained solid was dissolved in ethyl acetate (1100 mL) at 70° C., and hexane (400 mL) was dropwise added at 60° C. The mixture was allowed to cool to room temperature overnight. The resulting precipitate was collected by filtration, washed with hexane/ethyl acetate (1/1) 3 times, and dried to give the title compound (30.5 g) as a white solid.
