1: 67 percent / pyridine / 1.5 h / Ambient temperature 2: dicyclohexylcarbodiimide / pyridine / 168 h / Ambient temperature 3: NH3 / methanol / 32 °C 4: Raney Ni / H2O / 2 h / Ambient temperature 5: 37 °C / hydrolysis with snake venom phosphodiesterase in triethylammonium bicarbonate buffer View Scheme