Hydrochloric Acid → Methyl 5-(hydroxymethyl)-2-methoxybenzoate

Combine methyl 2-methoxy-5-formylbenzoate (0.1 g, 0.5 mmol) and tetrahydrofuran (2 mL). Cool in an ice bath. Add a solution of borane tetrahydrofuran complex (0.17 mL, 1 M in tetrahydrofuran, 0.17 mmol). After 1.5 hours, again add a solution of borane tetrahydrofuran complex (0.17 mL, 1 M in tetrahydrofuran, 0.17 mmol). After 2 hours, add a 1 M aqueous solution of hydrochloric acid (2 mL) and stir. After 15 minutes, dilute the reaction mixture with ethyl acetate. Separate the layers, extract the aqueous layer three times with ethyl acetate and combine the organic layers. Dry the organic layer over Na2SO4, filter, and evaporate in vacuo to give methyl 2-methoxy-5-hydroxymethylbenzoate: Rf=0.32 (silica gel, ethyl acetate).