To a stirred suspension of 1,3,5-tricarbamoylbenzene 1457 (4.6 g, 22.2 mmol) in DMF (35 mL), thionyl chloride (6 mL) was added over a period of 1 h, maintaining the temperature at 60 C°. Stirring at this temperature was maintained for 6 h, during which time complete dissolution occurred. The resulting solution was poured into dilute aq. HCl (100 mL) to decompose unreacted SOCl2, giving a dense white precipitate. This solid was collected by filtration, washed with water until the washings were neutral to litmus, and dried at 120 C° for 14 h. Crystallization from ethanol and acetone yielded the product 1458 as colorless needles (1.50 g, 45%).
