A solution of 4-(3-(tert-butylamino)-2-methylquinoxalin-5-yl)-1H-pyrrole-2-carboxamide (Example 420; 21.8 mg, 0.067 mmol), di(1H-imidazol-1-yl)methanone (CDI; Aldrich; 12.02 mg, 0.074 mmol), and NaH (60% w/w in mineral oil; 3.24 mg, 0.081 mmol) in a mixture of THF (1.0 mL) and DMF (0.10 mL) was stirred under argon at 23° C. for 1 h. Additional di(1H-imidazol-1-yl)methanone (12 mg, 0.074 mmol) was added, and the resulting mixture was stirred at 23° C. for 5 min. Additional di(1H-imidazol-1-yl)methanone (72 mg, 0.444 mmol) was added, and the resulting mixture was stirred at 23° C. for 5 min. The reaction mixture was subsequently concentrated onto silica gel and chromatographically purified (silica gel, 0-100% EtOAc/hexanes) to provide 6-(3-(tert-butylamino)-2-methylquinoxalin-5-yl)-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione (11.9 mg, 0.034 mmol, 51% yield) as a light-yellow solid. 1H NMR (400 MHz, CDCl3) δ ppm 8.06 (1H, s), 7.82 (1H, d, J=7.6 Hz), 7.66 (1H, dd, J=7.3, 1.3 Hz), 7.40 (1H, d, J=7.6 Hz), 7.32 (1H, d, J=0.7 Hz), 7.30 (0.5; H, br. s), 4.76 (1H, s), 4.05 (0.5; H, s), 2.56 (3H, s), 1.57 (9H, s). m/z (ESI, +ve) 350.0 (M+H)+.
