The general procedure for the synthesis of methyl 2,6-dihydroxybenzoate from 2,6-dihydroxybenzoic acid is as follows:
a) 80% sodium hydride (10.00 g, 333.3 mmol) was dissolved in N,N-dimethylformamide (45 mL) under argon protection and the solution was cooled to 0°C. Subsequently, a solution of 2,6-dihydroxybenzoic acid (48.88 g, 317.1 mmol) in N,N-dimethylformamide (50 mL) was slowly added over 45 minutes. After stirring for 45 minutes, iodomethane (21.0 mL, 337 mmol) was added dropwise over 20 minutes. The reaction mixture was stirred at room temperature for 70 hours. Upon completion of the reaction, the mixture was diluted with dichloromethane and filtered through a silica gel plug, using dichloromethane as the eluent. Finally, the solvent was evaporated to afford the target product methyl 2,6-dihydroxybenzoate (35.22 g, 66.1% yield). The product was characterized by 1H NMR (250 MHz, DMSO-d6): δ 9.91 (s, 2H), 7.09 (t, J = 1.2 Hz, J = 2.5 Hz, 1H), 6.37 (d, J = 1.1 Hz, 2H), 3.78 (s, 3H).
