General procedure for the synthesis of methyl 5-iodo-2-methylbenzoate from methanol and 5-iodo-2-methylbenzoic acid: Thionyl chloride (74 g, 0.62 mol) was added slowly and dropwise to a solution of 5-iodo-2-methylbenzoic acid (86 g, 0.57 mol) in methanol (0.5 L) at 0 °C. After the dropwise addition, the reaction mixture was heated to reflux and maintained for 2 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently concentrated under reduced pressure to remove the solvent. The concentrated residue was diluted with water and extracted with ethyl acetate (2 x 300 mL). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and finally concentrated under reduced pressure to afford the target product methyl 5-iodo-2-methylbenzoate (69 g, 73% yield), which could be used in subsequent reactions without further purification.
