[Synthesis]
Example 1 Synthesis of 2-(benzoyloxy)-2-methylpropionic acid: 2-hydroxyisobutyric acid (50 g) was dissolved in acetonitrile (480 mL). To this solution, pyridine (78 mL) was added as a base, followed by slow dropwise addition of benzoyl chloride (56 mL). The reaction mixture was stirred at room temperature for 40 minutes to complete the esterification reaction. Upon completion of the reaction, 2N hydrochloric acid (300 mL) was added to the mixture for acidification, followed by extraction with ethyl acetate (400 mL x 2) to separate the products. The organic phases were combined and dried with anhydrous magnesium sulfate. After filtration to remove the desiccant, the solvent was removed by distillation under reduced pressure. The resulting crude product was recrystallized using a tert-butyl methyl ether/n-heptane solvent mixture to give purified 2-(benzoyloxy)-2-methylpropanoic acid (82 g, 82% yield). The product was detected by thin layer chromatography (TLC) with an Rf value of 0.37 (unfolding agent: ethyl acetate). The NMR hydrogen spectrum (300 MHz, CDCl3) data were as follows: δ 8.20-9.40 (broad peak, 1H, COOH), 8.01-8.06 (multiple peaks, 2H, ArH), 7.53-7.59 (multiple peaks, 1H, ArH), 7.40-7.46 (multiple peaks, 2H, ArH), 1.73 (single peak, 6H, CH3). |