2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 2-Formyl-5-methoxy-3-methoxycarbonyl-1-methylindole

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Reaction Steps

5.0 g (19.0 mmol) of 5-methoxy-3-methoxycarbonyl-2-methoxymethyl -1-methylindole obtained in Example 2 or 4 was dissolved in 200 ml of anhydrous toluene, followed by the addition of 4.94 g (20.9 mmol) of DDQ and subsequent 2 hours of heating under reflux. After cooling the reaction mixture and removing impurities by filtration, the organic layer was washed with water and saturated sodium chloride aqueous solution and then dried over anhydrous magnesium sulfate. After anhydrous magnesium sulfate was filtered off and the solvent was distilled off under reduced pressure, the resulting residue was purified by a silica gel column chromatography (eluent: hexaneethyl acetate, 3:1) to obtain 3.38 g of the title compound with a yield of 72%.

Provenance & Evidence