To a mixture of 4-ethoxybenzoic acid (0.332 g, 2.00 mmol) and a few drops of N,N-dimethylformamide in methylene chloride (50 mL) cooled to 0° C. was added oxayl chloride (0.21 mL, 2.2 mmole). After 30 min reaction the mixture was warmed to room temperature and stirred for an additional 10 min. The mixture was concentrated in vacuo, and the residue dissolved in methylene chloride (10 mL), and the resulting solution added in two portions to a mixture of N1-(4-methoxybenzoyl)-1,2-benzenediamine (0.455 g, 2.00 mmol) and triethylamine (0.281 mL, 2.00 mmol) in methylene chloride (40 mL) cooled to 0° C. After 4 h, the mixture was allowed to warm to room temperature and stirred for an additional 12 h. The reaction was quenched with cold dilute aqueous hydrochloric acid (50 mL), diluted with hexane, and shaken in a separatory funnel. The organic layer was washed with cold dilute aqueous hydrochloric acid and saturated aqueous sodium bicarbonate solution. The solution was dried (magnesium sulfate), filtered, and concentrated in vacuo. Recrystallization of the residue from methylene chloride/hexane provided 317 mg (41%) of title compound.
