(1) Toluene (1.5 g), triphenyl phosphite (2.35 g), 2-hydroxy-4,5-dimethoxybenzoic acid (1.5 g) and concentrated sulfuric acid (40.3 μL) were mixed in a reaction flask under argon protection. The reaction mixture was refluxed under stirring conditions for 2.5 hours. After completion of the reaction, it was cooled to room temperature, methanol (5 g) was added and stirring was continued for 30 min. Subsequently, water (2.5 g) was added to the mixture and stirred for another 30 minutes. The precipitated crystals were filtered and dried under reduced pressure to afford phenyl 2-hydroxy-4,5-dimethoxybenzoate (2.0 g) in 96% yield.
