Benzoyl chloride (1.3 mL, 11 mmol) was added dropwise over 30 min to a stirred suspension of adenine (1.35 g, 10 mmol) in dry pyridine, and stirring was continued at 100 °C for a further 3 h, and the reaction mixture was allowed to stand overnight at room temperature. The reaction was quenched with methanol and the solvents were removed under reduced pressure. The residue was triturated in hot isopropanol and dried in vacuo to give 8 as a white solid: yield 2.15 g (90%). MS (+ESI): m/z 240 [M+H]+; 1H NMR (400 MHz, d-DMSO): δ11.50 (s, 1H), 8.74 (s, 1H), 8.52 (s, 1H), 8.11 (d, 2H, J = 7.2 Hz), 7.66 (t, 1H, J = 7.2 Hz), 7.58 (t, 2H, J = 7.2 Hz).
