3-Hydroxybenzaldehyde → Ethyl 2-(3-formylphenoxy)acetate

To a mixture of 3-hydroxybenzaldehyde (5.17 g, 42.34 mmol), K2CO3 (5.85 g) and acetone (50 ml) was added ethyl bromoacetate (5.2 ml). The reaction mixture was stirred at room temperature overnight, additional K2CO3 (1 equivalent) was added, the mixture was stirred for one hour, then additional ethyl bromoacetate (0.5 equivalents) was added and the mixture was stirred at room temperature until the reaction was complete. The reaction mixture was filtered, water was added to the filtrate and the solvent was removed. The residue was dissolved in ether, extracted with 1M NaOH (2×100 ml), and the ether layer was dried over MgSO4 and stripped to afford, as a liquid, 7.89 g of 3-(ethoxycarbonylmethoxy)benzaldehyde.