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, the reflux being maintained once it has started. At the end of the addition, the mixture is heated at reflux for one 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 one hour. After cooling to RT, the reaction mixture is poured into an ice/concentrated HCl mixture and extracted with EtOAc, the organic phase is washed with water, with 1N NaOH solution and dried over Na2SO4, and the solvent is evaporated off under vacuum. 6.5 g of the expected product are obtained after crystallization from a DCM/iso ether mixture (20/80; v/v),

Provenance & Evidence