5-chloro-1H-indole-2,3-dione → HCID 21905920, compound

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Reaction Steps

A solution of 25 g of 1-bromo-2-trifluoromethoxybenzene in 130 ml of ether is added dropwise to a mixture of 2.8 g of magnesium in 20 ml of ether, and once the refluxing has started it is maintained. At the end of the addition the mixture is refluxed for 1 hour. A mixture of 7.5 g of 5-chloro-1H-indole-2,3-dione in 100 ml of THF is then added, at a temperature below 40° C., followed by refluxing for 1 hour. After cooling to RT, the reaction mixture is poured into an ice/concentrated HCl mixture, the resulting mixture is extracted with EtOAc, the organic phase is washed with water, with 1N NaOH solution and dried over Na2SO4, and the solvent is evaporated under vacuum. 6.5 g of the expected product are obtained after crystallization from a DCM/iso-ether mixture (20/80; v/v); m.p.=214° C.

Provenance & Evidence