79 μl (0.567 mmol) of triethylamine and 55 μl (0.454 mmol) of n-valeroyl chloride are added to a suspension of 100 mg (0.378 mmol) of 5-aminomethyl-2,3-dimethoxy-7-nitro-quinoxaline in 2 ml of tert-butyl methyl ether and the mixture is stirred at room temperature for 16 hours. The mixture is then taken up in dichloromethane, washed with 1 N hydrochloric acid and with 1 N sodium hydroxide solution, dried over sodium sulfate and concentrated by evaporation. The title compound is obtained in the form of a yellowish powder.
