Acetic Acid → Methyl 3-acetyl-4-bromo-1-methyl-1H-indole-2-carboxylate

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Reaction Steps

33 ml of trifluoroacetic anhydride are added to a solution of 13.2 ml of acetic acid, of 1.6 ml of phosphoric acid and of 170 ml of acetonitrile, stirring is carried out for 10 min at room temperature and a solution of 20.6 g (77 mmol) of methyl 4-bromo-1-methyl-1H-indole-2-carboxylate in 120 ml of acetonitrile is added. The mixture is stirred for 4 h at room temperature and is poured onto water and extracted with ether. The organic phase is dried over sodium sulphate, the solvent is evaporated under reduced pressure and the residue is taken up in a mixture of cyclohexane and of dichloromethane. The precipitate is collected by filtration, washed with ether and dried under reduced pressure. 18.8 g (61 mmol) of product are obtained. The mother liquors are concentrated and the residue is purified by chromatography on a column of silica gel. 3.2 g (10 mmol) of additional product are isolated.

Provenance & Evidence