Step 1: 3-hydroxy-4-methylbenzoic acid (4.56 g, 30 mmol) was dissolved in methanol (60 mL) and thionyl chloride (40 drops) was added slowly and dropwise. The reaction mixture was heated to reflux and maintained for 18 hours. Upon completion of the reaction, the volatile components were removed by distillation under reduced pressure. The crude product was purified by fast column chromatography on silica gel, using gradient elution with ethyl acetate/heptane (2%-40%) to afford methyl 2-hydroxy-4-methylbenzoate (3.04 g, 61% yield) as a colorless oil. Mass spectrometry analysis (ESI/APCI+): m/z 167 ([M-H]-).
