An aqueous solution (7 ml) of sodium dihydrogenphosphate (4.01 g, 33.42 mmol), an aqueous solution (7 ml) of sodium chlorite (1.74 g, 19.33 mmol) and aqueous hydrogen peroxide (1.89 ml, 30%) were added to an acetonitrile solution (12 ml) of 3-(3,4,5,6-tetramethoxy-2-methylbenzyl)-2-benzyloxybenzaldehyde (1.87 g, 4.28 mmol) and the resulting solution was stirred at room temperature for 5 hours. The reaction solution was diluted with water and then extracted with ethyl acetate. The extract was washed with an aqueous saturated sodium hydrosulfite (Na2S2O4) solution and saturated brine, then dried and concentrated to obtain the titled compound (1.90 g, 4.20 mmol, 98%).
