2-n-Propoxybenzoyl chloride (7.27 g, 0.366 mol) was added dropwise to a stirred suspension of 2-amino-3-carbamoylbenzamide (Preparation 17; 2.63 g, 0.0147 mol) in pyridine (50 ml) at 0° C. The mixture was stirred at room temperature for 3 days, then the solvent evaporated under vacuum. The residue was treated with water (100 ml) and, on chilling the solution, colorless crystals formed. The product was collected by filtration and then suspended in a stirred mixture of sodium hydroxide (1.73 g, 0.043 mol), water (90 ml) and ethanol (20 ml). The mixture was heated under reflux for 3 hours, allowed to cool and filtered. The filtrate was acidified to pH 2 with concentrated hydrochloric acid and extracted with a methanoldichloromethane mixture (2:98, 3×100 ml). The organic extracts were combined, washed sequentially with saturated aqueous sodium carbonate solution (3×100 ml) and brine (3×50 ml), dried (Na2SO4) and evaporated under vacuum. Crystallization of the residue from ethyl acetate-methanol gave the title compound as a white solid (1 g, 40%), m.p. 226°-227° C. Found: C,67.00; H,5.40; N,12.90. C18H17N3O3 requires C,66.86; H,5.30; N,13.00%.
