Reaction Steps
2′,3′,5′-Tri-O-acetylguanosine 1 (4.6 g, 11.2 mmol, 1.0 eq), 37% aqueous formaldehyde (4.7 mL, 156 mmol, 14 eq), p-thiocresol (4.6 g, 37 mmol, 3.3 eq), and acetic acid (2 mL) were added into 50 mL of ethanol. The mixture was heated under reflux for 4 h. The mixture was cooled and the white precipitate was collected by filtration. Product was recrystallized from water to obtain the pure solid compound 2 in 75% yield (4.58 g, 8.4 mmol). TLC (CH2Cl2:MeOH, 9:1 v/v): Rf=0.57; 1H NMR (DMSO-d6, 400 MHz) δ (ppm): 2.03 (s, 6H), 2.09 (s, 3H), 2.25 (s, 3H), 4.26-4.29 (m, 1H), 4.30-4.34 (m, 1H), 4.9 (br.s, 2H), 5.48 (br.s, 1H), 5.77 (t, 1H), 5.97 (d, J=6.4 Hz, 1H), 6.1 (br.s, 1H), 6.54 (br.s, 1H), 7.11 (d, J=7.2 Hz, 2H), 7.3 (d, J=7 Hz, 2H), 7.9 (s, 1H), 10.7 (br.s, 1H); 13C NMR (DMSO-d6, 400 MHz) δ (ppm): 20.2, 20.4, 20.5, 63.5, 67.2, 70.3, 72.06, 79.55, 84.44, 129.53, 129.54, 135.67, 153.94, 156.69, 169.31, 169.49.
