1: 76.9 percent / TFA / 6 h / 60 - 80 °C 2: 73.5 percent / Dowtherm A / 1 h / 120 - 130 °C 3: 92.2 percent / conc. HNO3 / acetic acid / 2 h / Ambient temperature 4: 1.) POCl3, 2.) PhNEt2 / 1.) 70 - 90 deg C, 2.) 70 - 90 deg C, 3 h 5: 88.1 percent / conc. aq. NH4OH / dioxane / 0.25 h / 60 °C 6: tin, conc. aq. HCl / dioxane / Heating 7: conc. HCl, NaNO2 / H2O / 1 h View Scheme

1: 73.5 percent / Dowtherm A / 1 h / 120 - 130 °C 2: 92.2 percent / conc. HNO3 / acetic acid / 2 h / Ambient temperature 3: 1.) POCl3, 2.) PhNEt2 / 1.) 70 - 90 deg C, 2.) 70 - 90 deg C, 3 h 4: 88.1 percent / conc. aq. NH4OH / dioxane / 0.25 h / 60 °C 5: tin, conc. aq. HCl / dioxane / Heating 6: conc. HCl, NaNO2 / H2O / 1 h View Scheme

1: 92.2 percent / conc. HNO3 / acetic acid / 2 h / Ambient temperature 2: 1.) POCl3, 2.) PhNEt2 / 1.) 70 - 90 deg C, 2.) 70 - 90 deg C, 3 h 3: 88.1 percent / conc. aq. NH4OH / dioxane / 0.25 h / 60 °C 4: tin, conc. aq. HCl / dioxane / Heating 5: conc. HCl, NaNO2 / H2O / 1 h View Scheme

1: tin, conc. aq. HCl / dioxane / Heating 2: conc. HCl, NaNO2 / H2O / 1 h View Scheme