Methyl 2-oxoindole-6-carboxylate

334952-07-7

14192-26-8

General procedure for the synthesis of methyl 2-oxoindoline-6-carboxylate from methyl 4-(2-methoxy-2-oxoethyl)-3-nitrobenzoate: 48.3 g of methyl 4-(2-methoxy-2-oxoethyl)-3-nitrobenzoate was dissolved in 800 mL of concentrated acetic acid, and 5.0 g of 10% palladium carbon catalyst was added. The reaction mixture was hydrogenated in a hydrogen atmosphere at room temperature for 2.5 hr at a reaction temperature of 50 °C and a hydrogen pressure of 50 psi. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated to dryness. The residue was dissolved in 150 mL of tert-butyl methyl ether, filtered again and dried under vacuum at 100 °C. The resulting product was methyl 2-oxoindoline-6-carboxylate in a yield of 28.6 g (98% of the theoretical yield), with a thin layer chromatographic Rf value of 0.4 (silica gel plate, unfolding agent dichloromethane/methanol = 10:1) and a melting point of 208-211 °C.