General procedure for the synthesis of 2,5-bis-benzyloxybenzoic acid from the compound (CAS: 78283-37-1): 1.0 g (2.4 mmol) of the ester 25 and 0.19 g (4.7 mmol) of sodium hydroxide were dissolved in 15 mL of a solvent mixture of methanol, dioxane, and water (1:1:1, v/v), and stirred at reflux for 14 hours. After completion of the reaction, it was cooled to 25 °C and most of the organic solvent was removed by rotary evaporator. The residue was diluted with water, acidified with 1N HCl to pH < 7 and subsequently extracted twice with ethyl acetate (50 mL). The organic phases were combined, washed sequentially with water and saturated saline, dried over anhydrous magnesium sulfate, and concentrated. The crude product was purified by column chromatography using hexane and ethyl acetate (1:1, v/v) as eluents to afford 0.72 g (91% yield) of the target compound 13.1H NMR (δ, ppm): 11.06 (s, 1H), 7.81 (d, J = 3.1 Hz, 1H), 7.43-7.32 (m, 10H), 7.17 (dd, J = 9.0, 3.1 Hz, 1H), 7.07 (d, J = 9.0 Hz, 1H), 5.26 (s, 2H), 5.08 (s, 2H); 13C NMR (δ, ppm): 165.3, 153.9, 151.9, 136.6, 134.6, 129.4, 129.4, 128.8, 128.4, 128.2, 127.8, 123.0, 119.0, 117.8, 115.1, 73.2, 70.9.
