Synthesis
Methyl 3,5-dihydroxybenzoate (4-1) (5.0 g, 30 mmol) was used as a raw material, which was dissolved in a solvent mixture of methanol (70 mL) and NaHCO3 aqueous solution (70 mL, 1 M) at 0 °C. Aqueous potassium iodide solution (10 mL, 3.8 M) of iodine (7.4 g, 29.3 mmol) was slowly added via syringe pump (12 mL/min). After 1 h of reaction, the reaction solution was acidified to pH 2 with 37% HCl and then gradually warmed up to room temperature. The reaction mixture was concentrated to dryness and the product was purified by recrystallization from methanol-water system. Methyl 3,5-dihydroxy-4-iodobenzoate (4-2) in yellow crystalline form was finally obtained (4.4 g, 14.8 mmol, 49% yield).LCMS analysis: calculated value 293.94, measured value 293.03 (M-).
References
[1] Organic Letters, 2016, vol. 18, # 3, p. 360 - 363
[2] Organic Process Research and Development, 2010, vol. 14, # 1, p. 180 - 187
[3] European Journal of Organic Chemistry, 2012, # 1, p. 188 - 192
[4] Patent: US2015/50659, 2015, A1. Location in patent: Page/Page column
[5] Patent: US2016/237279, 2016, A1. Location in patent: Paragraph 0281-0282
