Benzene → Methyl 4-[(methylamino)carbonyl]benzoate

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Reaction Steps

Monomethylterephthalate (Aldrich, 5.0 g, 0.028 mol) was added to 80 mL of dry benzene in a 250-mL round-bottom flask under argon and fitted with a calcium chloride drying tube. Dry pyridine (4.4 g, 0.056 mol) was added and the mixture was stirred for 15 min. Oxalyl chloride (3.66 g, 0.029 mol) was added by drop over 10 min. The mixture bubbled vigorously during the addition and a heavy white precipitate formed. The mixture was vigorously stirred for 40 min and followed by TLC (three solvent systems: dichloromethane, 2% methanol, and 5% methanol). Anhydrous methylamine was bubbled into the mixture for 10 min. The precipitate dissipated somewhat and the solution color changed from colorless to green and finally to yellow. The mixture was then stirred overnight. The remaining white precipitate was collected on a filter and washed with benzene. The filtrate was washed with water and dried over sodium sulfate. The drying agent was removed by filtration, washed with benzene, and the solvent concentrated to give a white solid. The solids were combined and dissolved in 300 mL dichloromethane. The solution was washed 3 times with 5% HCl, 3×5% sodium bicarbonate, 3×water, 1×brine, and then dried over sodium sulfate. The drying agent was removed by filtration and the filtrate concentrated to give a white solid which was dried in vacuo. This white solid was recrystallized from methanol to give 2 g (37%) of methyl 4-(methylaminocarbonyl)benzoate, mp 126° C.

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