(2) Synthesis of 4-methoxy-2,3,6-trimethylbenzenesulfonyl chloride: 4.5 g of 2,3,5-trimethylanisole was dissolved in 500 mL of dichloromethane and the reaction system was cooled to -5 °C to -10 °C. The reaction system was then cooled to -5 °C to -10 °C. The reaction system was then cooled to -5 °C to -10 °C. Subsequently, 6.0 mL of a dichloromethane solution of chlorosulfonic acid (400 mL) was added slowly and dropwise. After completion of the reaction mixture with stirring at room temperature, the reaction was quenched by pouring it into an ice-5% aqueous NaHCO3 solution. The organic phase was separated and the aqueous phase was extracted with dichloromethane. The organic layers were combined, washed with water and dried with anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure and the residue was recrystallized by hexane and filtered to give white crystals. Yield 5.0 g (yield 67.0%), melting point 56°C-58°C. Elemental analysis (C10H13O3SCl) Calculated values: C, 48.29; H, 5.27; S, 12.89; Cl, 14.26; Measured values: C, 48.42; H, 5.21; S, 12.61; Cl, 14.25.
