To a stirred solution of 4-dibenzylamino-2,5-dimethylbenzaldehyde (3.60 g, 10.9 mmol) in toluene (35.0 mL) under nitrogen was added 1,2-ethanediol (1.83 mL, 32.8 mmol) and p-toluenesulfonic acid (451 mg, 2.62 mmol). The reaction mixture was heated at 80° C. overnight. TLC (3:1 hexanes:EtOAc) showed a ˜50:50 mixture of product and starting material. Magnesium sulfate (1.32 g, 10.9 mmol) was added and stirring was continued for 6 h. The reaction mixture was then filtered and concentrated under reduced pressure to give title compound (3.19 g, 78% yield) as an oil.
