water; hydrogen bromide T=110°C; 6 h; Inert atmosphere;

1: 67 percent / K2CO3 / dimethylsulfoxide / 120 °C 2: 74 percent / H2, thiophene / 5percent Pd/C / 2-methoxy-ethanol; methanol / 50 °C / Heating 3: 61 percent / pyridine / CHCl3 / 3 h 4: 63 percent / hydrazine hydrate / dioxane / 3 h / Heating 5: 28 percent / NaOAc / butan-1-ol 6: 57 percent / KOH / dimethylsulfoxide / 14 h 7: 38 percent / 48percent aq. HBr / Heating View Scheme

1: 67 percent / K2CO3 / dimethylsulfoxide / 120 °C 2: 74 percent / H2, thiophene / 5percent Pd/C / 2-methoxy-ethanol; methanol / 50 °C / Heating 3: 61 percent / pyridine / CHCl3 / 3 h 4: 63 percent / hydrazine hydrate / dioxane / 3 h / Heating 5: 28 percent / NaOAc / butan-1-ol 6: 57 percent / KOH / dimethylsulfoxide / 14 h 7: 38 percent / 48percent aq. HBr / Heating View Scheme

1: 74 percent / H2, thiophene / 5percent Pd/C / 2-methoxy-ethanol; methanol / 50 °C / Heating 2: 61 percent / pyridine / CHCl3 / 3 h 3: 63 percent / hydrazine hydrate / dioxane / 3 h / Heating 4: 28 percent / NaOAc / butan-1-ol 5: 57 percent / KOH / dimethylsulfoxide / 14 h 6: 38 percent / 48percent aq. HBr / Heating View Scheme

1: 57 percent / KOH / dimethylsulfoxide / 14 h 2: 38 percent / 48percent aq. HBr / Heating View Scheme

1: 61 percent / pyridine / CHCl3 / 3 h 2: 63 percent / hydrazine hydrate / dioxane / 3 h / Heating 3: 28 percent / NaOAc / butan-1-ol 4: 57 percent / KOH / dimethylsulfoxide / 14 h 5: 38 percent / 48percent aq. HBr / Heating View Scheme

1: 28 percent / NaOAc / butan-1-ol 2: 57 percent / KOH / dimethylsulfoxide / 14 h 3: 38 percent / 48percent aq. HBr / Heating View Scheme

1: 63 percent / hydrazine hydrate / dioxane / 3 h / Heating 2: 28 percent / NaOAc / butan-1-ol 3: 57 percent / KOH / dimethylsulfoxide / 14 h 4: 38 percent / 48percent aq. HBr / Heating View Scheme