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General procedure for the synthesis of methyl 2-amino-4-iodobenzoate from methanol and 2-acetamido-4-iodobenzoic acid (CAS:117324-10-4): 16.1 g of 2-acetamido-4-iodobenzoic acid (melting point 233°C-235°C; synthesized according to U.S. Patent 4,762,838) was dissolved in 325 ml of anhydrous methanol, cooled to 0°C and passed through a dry hydrogen chloride gas to saturation. The reaction mixture was heated to reflux for 15 hours, cooled to room temperature and again passed through dry HCl gas to saturation, followed by standing at room temperature for 24 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure and the residue was dissolved in dichloromethane. The organic phase was washed to neutrality with saturated aqueous sodium bicarbonate to remove unreacted acid. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure to give 13.8 g of methyl 2-amino-4-iodobenzoate with a melting point of 63°C-67°C.

[1] Patent: WO2006/41773, 2006, A2. Location in patent: Page/Page column 303-304
[2] Patent: US2017/121294, 2017, A1. Location in patent: Paragraph 0058