Hydrochloric Acid → 4-(3-Formyl-6-nitroindol-1-yl)benzoic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-(6-nitroindol-1-yl)benzoic acid ethyl ester (0.53 g) in N,N-dimethylformamide (6 mL) was added phosphoryl chloride (0.31 g) under ice cooling and this mixture was stirred at 70° C. overnight. After cooling to ambient temperature, to this reaction mixture was added 2 mol/L aqueous sodium hydroxide solution and this mixture was stirred at 30 minutes. This reaction mixture was poured into 1 mol/L hydrochloric acid, and the precipitated solid was collected by filtration, and washed with water and n-hexane, and dried under reduced pressure at 40° C. to give 4-(3-formyl-6-nitroindol-1-yl)benzoic acid ethyl ester (0.46 g). To a solution of this aldehyde (0.46 g) in tetrahydrofuran (10 mL) were added hydroxylamine hydrochloride (0.19 g) and pyridine (0.43 g) at room temperature, and this mixture was stirred at 80° C. for 8 hours. To this reaction mixture was added acetic anhydride (0.42 g) at 80° C., this mixture was stirred at same temperature overnight. After cooling to ambient temperature, to this reaction mixture was added 1 mol/L hydrochloric acid, and the precipitated solid was collected by filtration. This solid was washed with water, n-hexane and diethyl ether to give the title compound (0.13 g).

Provenance & Evidence