To a mixture of 5-bromoveratraldehyde (980 mg, 4.0 mmol) and malononitrile (246 mg, 4.0 mmol) in ethanol (10 mL) was added piperidine (0.4 mL) and 2,3-diaminophenol (496 mg, 4.0 mmol). The mixture was stirred at room temperature under argon for 2 h then diluted with water (20 mL). The precipitate was filtered to yield brown solid, yielding 1.367 g (85%) of the title compound. 1H NMR (CD3OD): 6.25 (s, 1H), 6.18 25 (s, 1H), 6.34 (d, J=7.8, 1H), 6.10 (d, J=7.8, 1H), 4.43 (s, 1H), 3.68 (s, 3H), 3.64 (s, 3H).
