1: 100 percent / n-Bu4NF*3H2O / tetrahydrofuran / 1.5 h / -21 - -17 °C 2: 846 mg / CrO3, pyridine / CH2Cl2 / 0.5 h / Ambient temperature 3: NH3 / methanol / 20 h / Ambient temperature 4: 82 percent / TFA / H2O / 5 h / Ambient temperature View Scheme

1: 100 percent / n-Bu4NF*3H2O / tetrahydrofuran / 1.5 h / -21 - -17 °C 2: 846 mg / CrO3, pyridine / CH2Cl2 / 0.5 h / Ambient temperature 3: NH3 / methanol / 20 h / Ambient temperature View Scheme

n-BuNF in tetrahydrofuran T=-20°C;