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Example 1: Synthesis of 2-methylmercaptobenzoxazole 2-Mercaptobenzoxazole (C-1, 1200 g, 7.94 mol) and 8500 mL of ethyl acetate were added to a 20 L three-necked flask and stirred until completely dissolved. Subsequently, potassium carbonate (1420 g, 10.29 mol) was added slowly at room temperature. Iodomethane (1243 g, 8.76 mol) was added dropwise while keeping the internal temperature of the reaction system below 40 °C. After the dropwise addition, the reaction mixture was stirred continuously for 24 hours at 20°C. After completion of the reaction, 4000 mL of water and 138 g of ammonia (NH4OH) were added to the mixture and stirred for 20 min at room temperature. The organic layer was separated and the aqueous phase was extracted with 1200 mL of ethyl acetate. The organic layers were combined and washed with 1500 mL of water. The organic phase was concentrated under reduced pressure to about 2000 mL, dried by adding magnesium sulfate and filtered. The filtrate was further concentrated under reduced pressure to give 1288 g of Intermediate C-2 in 98% yield and 99.6% HPLC purity.