sulfuric acid; sodium nitrite in water T=-5°C; 2 h;

1: 60 percent / AcOH; H2SO4; I2 / periodic acid / H2O / 5 h / 55 °C 2: 85 percent / pyridine / 12 h / 20 °C 3: 64 percent / HBF4; NaNO2 / H2O / 2 h / -5 °C 4: 88 percent / H2SO4 / methanol; H2O / 12 h / 25 °C 5: H2SO4; NaNO2 / H2O / 2 h / -5 °C View Scheme

1: 85 percent / pyridine / 12 h / 20 °C 2: 64 percent / HBF4; NaNO2 / H2O / 2 h / -5 °C 3: 88 percent / H2SO4 / methanol; H2O / 12 h / 25 °C 4: H2SO4; NaNO2 / H2O / 2 h / -5 °C View Scheme

1: 88 percent / H2SO4 / methanol; H2O / 12 h / 25 °C 2: H2SO4; NaNO2 / H2O / 2 h / -5 °C View Scheme

1: 64 percent / HBF4; NaNO2 / H2O / 2 h / -5 °C 2: 88 percent / H2SO4 / methanol; H2O / 12 h / 25 °C 3: H2SO4; NaNO2 / H2O / 2 h / -5 °C View Scheme