6979-94-8

108-24-7

118-00-3

6979-94-8

2.2 mL of acetic anhydride (22 mmol) was added slowly and dropwise to a suspension of guanosine (2 g, 7.0 mmol) that had been pre-dried for 2 days under high vacuum with P4O10 containing triethylamine (7.7 mL, 55.2 mmol) and N,N-dimethylaminopyridine (92 mg, 0.75 mmol) in 27 mL of acetonitrile, and the reaction was carried out at 0°C. The mixture was stirred until homogeneous and the reaction was subsequently continued for 3 h at room temperature. After completion of the reaction, the reaction was quenched with methanol (2.3 mL). The reaction volume was concentrated to 1/3 of the original volume using a rotary evaporator, followed by the slow addition of ether to induce the precipitation of a fine white powder. The product was collected by filtration, washed with ether, and then stirred with acetone (30 mL) at 50 °C for 2 hours. A final 2.8 g (98% yield) of fine white powder product was obtained. The product was confirmed by 1H NMR (200 MHz, DMSO) and 13C NMR (200 MHz, CDCl3) analysis, and the mass spectrometry results were in accordance with the theoretical values (C18H21N5O5 [M+H]+ calculated value: 410.1306, measured value: 410.1305).