4-[(4-amino-3-nitrophenyl)oxy]-3-(methyloxy)benzaldehyde (2.42 g, 8.4 mmol), ethyleneglycol (4 ml) and p-toluenesulfonic acid (50 mg) in 50 mL of toluene was heated at 125 degrees Centigrade with a Dean-Stark trap for approximately 18 hours. The reaction mixture was diluted with ethyl acetate and washed twice with saturated NaHCO3. The aqueous layers were extracted with ethyl acetate. The organic layers were combined, dried over MgSO4 and concentrated to give 4-{[4-(1,3-dioxolan-2-yl)-2-(methyloxy) phenyl]oxy}-2-nitroaniline. (M+1) 332.9, 2.13 min (LC/MS method B)
