General procedure for the synthesis of imidazo[1,5-a:1',5'-d]pyrazine-5,10-dione from 1H-imidazole-4-carboxylic acid: 1H-imidazole-4-carboxylic acid (5 g, 44.6 mmol) was suspended in thionyl chloride (75 mL), and heated and refluxed under stirring for 18 hours. After completion of the reaction, the reaction mixture was cooled, filtered, washed with toluene and dried under high vacuum to afford the target compound imidazo[1,5-a:1',5'-d]pyrazine-5,10-dione as a yellow solid in 95% yield. Molecular formula: C8H4N4O2, molecular weight: 188.14 g/mol, melting point: 265-268°C. 1H NMR (300 MHz, DMSO-d6) δ: 8.24 (d, 1H, CHC-CO), 8.32 (d, 1H, CHC-CO, J=3Hz), 8.88 (d, 1H, CHN), 9.28 (d, 1H , CHN, J=3Hz).13C NMR (100 MHz, DMSO-d6) δ: 123.99, 124.52, 125.62, 137.26, 139.73, 150.39, 159.68.MS (ESI+, QTof, m/z): 189.0 [M + H]+.
![5H,10H-DIIMIDAZO[1,5-A:1', 5'-D] PYRAZINE-5,10-DIONE](/CAS/GIF/53525-65-8.gif)