manganese(IV) oxide in 1,4-dioxane; N,N-dimethyl-formamide 1.) 90 deg C, overnight, 2.) 105 deg C, 4 h;

1: 1.) p-toluenesulfonic acid / 1.) dioxane, reflux, 0.5 h, 2.) dioxane, H2O, reflux, 1 h 2: 58.1 g / KOH / tetrahydrofuran; methanol 3: 79 percent / 75percent aq. CH3COOH / 3 h / Heating 4: 30.9 g / 20percent aq. HCl / propan-1-ol / 7 h / Heating 5: 80 percent / 85percent hydrazine hydrate / ethanol / 7 h / Heating 6: 60 percent / MnO2 / dimethylformamide; dioxane / 1.) 90 deg C, overnight, 2.) 105 deg C, 4 h View Scheme

1: 30.9 g / 20percent aq. HCl / propan-1-ol / 7 h / Heating 2: 80 percent / 85percent hydrazine hydrate / ethanol / 7 h / Heating 3: 60 percent / MnO2 / dimethylformamide; dioxane / 1.) 90 deg C, overnight, 2.) 105 deg C, 4 h View Scheme

1: 80 percent / 85percent hydrazine hydrate / ethanol / 7 h / Heating 2: 60 percent / MnO2 / dimethylformamide; dioxane / 1.) 90 deg C, overnight, 2.) 105 deg C, 4 h View Scheme

1: 58.1 g / KOH / tetrahydrofuran; methanol 2: 79 percent / 75percent aq. CH3COOH / 3 h / Heating 3: 30.9 g / 20percent aq. HCl / propan-1-ol / 7 h / Heating 4: 80 percent / 85percent hydrazine hydrate / ethanol / 7 h / Heating 5: 60 percent / MnO2 / dimethylformamide; dioxane / 1.) 90 deg C, overnight, 2.) 105 deg C, 4 h View Scheme

1: 79 percent / 75percent aq. CH3COOH / 3 h / Heating 2: 30.9 g / 20percent aq. HCl / propan-1-ol / 7 h / Heating 3: 80 percent / 85percent hydrazine hydrate / ethanol / 7 h / Heating 4: 60 percent / MnO2 / dimethylformamide; dioxane / 1.) 90 deg C, overnight, 2.) 105 deg C, 4 h View Scheme