1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 3 h / 20 - 90 °C / Inert atmosphere 2: water; sodium hydroxide / methanol / 1 h / 20 °C View Scheme

1.1: toluene-4-sulfonic acid / dichloromethane / 0.17 h / 20 °C / Inert atmosphere 2.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -70 °C / Inert atmosphere 2.2: 3 h / 20 °C / Inert atmosphere 3.1: toluene-4-sulfonic acid / ethanol / 3 h / 20 °C / Inert atmosphere 4.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 4.2: 0.5 h / -35 - -5 °C 5.1: tetrahydrofuran / 0.25 h / 0 °C / Inert atmosphere 6.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 6.2: 0.5 h / -35 - -5 °C 7.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 3 h / 20 - 90 °C / Inert atmosphere 8.1: water; sodium hydroxide / methanol / 1 h / 20 °C View Scheme

1.1: tetrahydrofuran / 0.25 h / 0 °C / Inert atmosphere 2.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 2.2: 0.5 h / -35 - -5 °C 3.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 3 h / 20 - 90 °C / Inert atmosphere 4.1: water; sodium hydroxide / methanol / 1 h / 20 °C View Scheme

1.1: toluene-4-sulfonic acid / ethanol / 3 h / 20 °C / Inert atmosphere 2.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 2.2: 0.5 h / -35 - -5 °C 3.1: tetrahydrofuran / 0.25 h / 0 °C / Inert atmosphere 4.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 4.2: 0.5 h / -35 - -5 °C 5.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 3 h / 20 - 90 °C / Inert atmosphere 6.1: water; sodium hydroxide / methanol / 1 h / 20 °C View Scheme

1.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 1.2: 0.5 h / -35 - -5 °C 2.1: tetrahydrofuran / 0.25 h / 0 °C / Inert atmosphere 3.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 0.67 h / -70 - -35 °C 3.2: 0.5 h / -35 - -5 °C 4.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 3 h / 20 - 90 °C / Inert atmosphere 5.1: water; sodium hydroxide / methanol / 1 h / 20 °C View Scheme

1: 88 percent / Ac2O / Heating 2: 94 percent / 18percent KOH / 0.17 h / Heating View Scheme

1: methanol; hydrazine hydrate; potassium hydroxide 2: diethyl ether; pyridine; thionyl chloride / -15 °C 3: diethyl ether 4: methanol. KOH-solution View Scheme

1: thionyl chloride 2: diethyl ether; pyridine 3: aqueous hydrochloric acid 4: hydrazine hydrate; sodium ethylate; ethanol / 200 °C View Scheme

1: diethyl ether; pyridine 2: aqueous hydrochloric acid 3: hydrazine hydrate; sodium ethylate; ethanol / 200 °C View Scheme

1: aqueous hydrochloric acid 2: hydrazine hydrate; sodium ethylate; ethanol / 200 °C View Scheme