To a stirred solution of 5-aminophthalide (11.7 g, 78 mmol) and 2,4-dimethoxybenzaldehyde (15.5 g, 93.6 mmol) in 1% AcOH/DMF (60 ml), was added sodium triacetoxyborohydride (50.0 g, 236 mmol). The mixture was stirred at room temperature for 16 hours, diluted with EtOAc (400 ml), washed with saturated NaHCO3 solution (3×400 ml) and water (400 ml), dried over anhydrous Na2SO4, and evaporated to provide a crude product. Trituration of the crude product with MEOH gave 5-(2,4-dimethoxy-benzylamino)-3H-isobenzofuran-1-one as an off-white powder (19.0 g, 82%).
