[CH3:1][O:2][C:3](=[O:15])[C:4]1[CH:13]=[CH:12][C:7]([C:8]([O:10][CH3:11])=[O:9])=[CH:6][C:5]=1[NH2:14].CC(O)=O.[O-:20][C:21]#[N:22].[K+].[O-]C#N>O>[NH2:22][C:21]([NH:14][C:5]1[CH:6]=[C:7]([C:8]([O:10][CH3:11])=[O:9])[CH:12]=[CH:13][C:4]=1[C:3]([O:2][CH3:1])=[O:15])=[O:20]
To a 1 L flask charged with 2-aminoterephthalic acid dimethyl ester (29.4 g, 141 mmol) was added AcOH (160 mL) and the suspension heated to 60° C. until a solution was formed. A solution of potassium cyanate (23.4 g, 288 mmol) in water (50 mL) was then added to the stirred solution at 60° C. Effervescence was seen and a white ppt crashed out immediately, hindering stirring. AcOH was added (70 mL) to aid stirring and the suspension was stirred at 75° C. for 7 hrs. Another 1 eq of cyanate added portion wise (dry). More effervescence was seen and the reaction left for 16 hours at 70° C. The reaction was cooled to 0° C. and the product ppt was filtered off, the flask washed with water to get all product out. The material was washed with water (150 mL) and air dried o/n under vacuum. The crude product was suspended in MeOH (300 mL) and stirred under reflux for 1 hour. The suspension was cooled to room temperature and filtered. The product was washed with cold MeOH (300 mL) and ether and dried in vacuo to afford the title compound as a white solid, 31.5 g, 89%. 1H NMR (400 MHz, DMSO-D6) δ ppm 9.71 (1H, s) 8.97 (1H, s) 7.98 (1H, d, J=8.08 Hz) 7.46-7.57 (1H, m) 6.73 (2H, s) 3.88 (6H, s).
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