m-Chloroperbenzoic acid → 9-Fluoro-6-(p-toluenesulfonyloxy)benzo[g]isoquinoline-5,10-dione-2-oxide

Participants

Reaction Steps

A solution of 3-chloroperoxybenzoic acid (3.92 g; 55% titre) in dichloromethane (50 mL) is dropped during 5 min into a mixture of 9-fluoro-6-(p-toluenesulfonyloxy)benzo[g]isoquinoline-5,10-dione (1.98 g) in dichloromethane (20 mL). Care is taken to avoid the addition of the aqueous layer that separates from the dichloromethane solution of 3-chloroperoxybenzoic acid. An exothermic reaction ensues, and at the end of the addition the mixture is refluxed overnight. After cooling to room temperature the reaction mixture is diluted with dichloromethane (50 mL) and the organic solution is washed with water (3×30 mL). After drying over sodium sulfate the organic solution is concentrated to a volume of about 20 mL, diluted with absolute ethanol (30 mL) and concentrated to a small volume. After stirring at 0° C. for 1 h a yellow solid separates which is filtered, to give 9-fluoro-6-(p-toluenesulfonyloxy)benzo[g]isoquinoline-5,10-dione-2-oxide (1.35 g).

Provenance & Evidence