In a flask equipped with a mechanical stirrer, thermometer, reflux condenser, dropping funnel and heating jacket, a solution of 4,6-dichloro-5-(2-methoxyphenoxy)-2,2'-bipyrimidine (105 g) and 4-(tert-butyl)benzenesulfonamide (64.1 g, 0.30 mol) in DMSO (525 mL) was added. To this suspension was added potassium carbonate (83 g, 0.60 mol). The reaction mixture was heated to 100-105 °C under stirring and maintained for 3-4 hours. The reaction progress was monitored by HPLC. After completion of the reaction, the solution was cooled to 20-25 °C. Water (875 mL) was added slowly dropwise over 10-15 minutes and stirring was continued for 1 hour. The precipitated solid was collected by filtration, washed with water (2 x 350 mL) and subsequently transferred to a mortar. Water (800 mL) and concentrated hydrochloric acid (50 mL) were added and stirred for 30 minutes. The precipitated solid was collected by filtration again and washed with water (2 × 200 mL) and acetone (2 × 175 mL) sequentially. The solid was dried under reduced pressure at 40±2 °C for 16-24 h to afford the milky white solid product N-[6-chloro-5-(2-methoxyphenoxy)[2,2'-dipyrimidin]-4-yl]-4-tert-butylbenzenesulfonamide in a yield of 157.8-158.7 g (100% yield).
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