Two alternative solution phase routes for purine library synthesis
Reagents and conditions: (a) R1OH (2 equiv), DEAD (1.1 equiv), Ph3P (2 equiv), THF, -10→25 °C; (b) (CF3)2O, CH2Cl2, 0→25 °C; (c) R2OH (2 equiv), DEAD (1 equiv), Ph3P (2 equiv), THF, 0→25 °C; K2CO3, MeOH; (d) R3R4NH (4 equiv), DIEA, n-BuOH, 110 °C; AcOH/H2O/THF (3/1/1); (e) R1OH (1.2 equiv), DEAD (1.3 equiv), Ph3P (1.3 equiv), THF, -10→25 °C; (f) R2R3NH (1 equiv), DIEA, n-BuOH, 140 °C; (g) R4NH2 (1.5 equiv), DIEA, n-BuOH, 150–170 °C.