79 g (370 mmol) of sodium metaperiodate are added in portions to a vigorously stirred solution of 48 g (185 mmol) of tert-butyl (2E)-3-(4-cyano-2-methoxyphenyl)acrylate, 207 mg (0.81 mmol) of osmium tetroxide and 1.4 g (6.14 mmol) of benzyltriethylammonium chloride in 750 ml of water/THF (2:1), keeping the reaction temperature below 30° C. The solution is stirred at RT for a further 1 h. Water (2000 ml) is added, and the mixture is filtered. The remaining solid is dissolved in ethyl acetate and washed with a saturated sodium chloride solution. The organic phase is dried over magnesium sulfate and concentrated. The residue is stirred with petroleum ether. 21.18 g (71% of theory) of 4-cyano-2-methoxybenzaldehyde (4-formyl-3-methoxybenzonitrile) is obtained as a white solid.
