To a solution of 3-(3,4,5,6-tetramethoxy-2-methylbenzyl)-2-benzyloxybenzaldehyde (1.87 g, 4.28 mmol) in acetonitrile (12.0 ml) were added an aqueous solution (7.0 ml) of sodium dihydrogen phosphate (4.01 g, 33.42 mmol), an aqueous solution (7.0 ml) of sodium hypochlorite (1.74 g, 19.33 mmol) and an aqueous hydrogen peroxide (1.89 ml, 30%) and the mixture was stirred at room temperature for 5 hours. The reaction solution was diluted with water and extracted with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium hydrosulfite (Na2S2O4) and a saturated saline, dried and concentrated to give the title compound (1.90 g, 4.20 mmol, 98%).
