p-Toluenesulfonic acid → 3-methyl-4-(1-methyl-3-indolyl)-1H-pyrrole-2,5-dione

Participants

Reaction Steps

A solution of 802 mg of pentafluorophenyl pyruvate in 20 ml of dichloromethane was added dropwise to a solution of 266 mg (1 mmol) of isopropyl 1-methyl-3-indoleacetimidate hydrochloride and 808 mg (8 mmol) of triethylamine in 20 ml of dichloromethane. After completion of the addition, the mixture was stirred at room temperature for 18 hours. Then, 1.9 g (10 mmol) of p-toluenesulfonic acid were added and stirring was continued for 1 hour. The solvent was removed under reduced pressure. The residue was purified by flash chromatography on silica gel using ethyl acetate/dichloromethane (1:8) for the elution to give 24 mg(10% ) of 3-methyl-4-(1 -methyl-3-indolyl)- 1H-pyrrole-2,5-dione in the form of a yellow solid of melting point 181° C.

Provenance & Evidence