1step/89% 2,5-dimethoxybenzaldehyde from p-dimethoxybenzene
Fri Sep 23, 2005 9:28 am
Synlett 2004, 9, 1575
Summary:
10 mmol p-dimethoxybenzene, 3 g (100 mmol) paraformaldehyde, 0.25 mg (0.0025 mmol) H2SO4 and 4.54 g (20 mmol) DDQ were stirred in 10 mL MeCN for 5 h at 80 °C. The reaction mixtures were then cooled and the precipitate containing the DDHQ product was filtered and washed twice with EtOAc. The filtrate containing the aryl aldehyde products was purified by flash chromatography.
89% yield, 99% pure.
The 2,3-dichloro-5,6-dicyanohydroquinone (DDHQ) formed in the reaction can be recovered and re-oxidized to DDQ with nitric acid.