Diethyl Ether → 3-(Benzyloxy)-2-hydroxybenzaldehyde

To magnesium (2.9 g, turnings, 0.12 mol) in a mixture of anhydrous ether (85 mL) and benzene (85 mL) at 0° C., bromine (3.4 mL, 0.066 mol) was added dropwise. When the reaction had started, stirring was commenced and the addition of bromine continued until complete. The ice bath was removed and the reaction mixture was heated until the solution was almost colorless. After cooling down, the reaction mixture was slowly added to a solution of 2,3-bis-benzyloxy-benzaldehyde (128, 20 g, 0.063 mol) in benzene (415 mL) at room temperature while stirring vigorously. Upon completion of the addition, the reaction mixture was stirred at room temperature overnight, and then refluxed for 36 hours. After the reaction mixture was cooled down to room temperature, a solid was collected by filtration and washed with benzene, then boiled in hydrochloric acid (100 mL, 1.0 M) for 30 minutes. After cool down, the solution was extracted with dichloromethane. The organic layer was washed with brine and dried over magnesium sulfate. A light tan solid was obtained after removal of the solvent (129, 12.5 g, 87%).