1: NaNO2, aq. HBF4 2: Cu / acetone 3: N2H4, aq. HBr / ethane-1,2-diol / 170 - 190 °C View Scheme

1: With tetrafluoroboric acid; sodium nitrite in tetrahydrofuran; water T=0°C; 1 h; 2: With palladium diacetate in tetrahydrofuran; water T=0 - 60°C; 0.5 h;