1: phosphorus tribromide / diethyl ether / 3 h / 0 °C / Inert atmosphere 2: N,N-dimethyl-formamide / 15 h / 60 °C / Inert atmosphere 3: sodium tetrahydroborate / methanol; water / Inert atmosphere View Scheme

1: potassium hydroxide / water / 2 h / 90 °C / Inert atmosphere 2: N,N-dimethyl-formamide / 15 h / 60 °C / Inert atmosphere 3: sodium tetrahydroborate / methanol; water / Inert atmosphere View Scheme

1.1: toluene / 24 h / 120 °C 2.1: hydrogenchloride; water / ethanol / 1.5 h / 80 °C 2.2: pH 14 View Scheme

1.1: n-butyl-magnesium chloride; methyllithium / tetrahydrofuran / 0.5 h / -10 - 0 °C 1.2: 1 h 1.3: 1 h / 40 °C 2.1: thionyl chloride; sodium hydroxide / isopropanol acetate 2.2: 4 h / 50 °C 3.1: potassium hydroxide / diethylene glycol dimethyl ether / 42 h / 120 °C View Scheme

1.1: sodium hydride / N,N-dimethyl-formamide; toluene / 10 h / 80 °C 1.2: 2 h / 110 °C 1.3: pH 9 2.1: sulfur / 7 h / 110 °C 3.1: sodium hydroxide; water / ethanol / 17 h / 80 °C 3.2: pH 2 4.1: N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; benzotriazol-1-ol / N,N-dimethyl-formamide / 12 h / 20 °C 5.1: sodium tetrahydroborate; acetic acid / 1,4-dioxane / 3.5 h / 10 - 105 °C 6.1: hydrogenchloride / water / 30 °C 6.2: 1 h / 0 - 20 °C 6.3: 1 h 7.1: sodium hydroxide / ethanol; water / 0.5 h / 60 °C / Inert atmosphere 7.2: 12 h / 60 °C / Inert atmosphere 8.1: toluene / 24 h / 120 °C 9.1: hydrogenchloride / ethanol / 1.5 h / 80 °C / Reflux 9.2: pH 14 View Scheme

1.1: N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; benzotriazol-1-ol / N,N-dimethyl-formamide / 12 h / 20 °C 2.1: sodium tetrahydroborate; acetic acid / 1,4-dioxane / 3.5 h / 10 - 105 °C 3.1: hydrogenchloride / water / 30 °C 3.2: 1 h / 0 - 20 °C 3.3: 1 h 4.1: sodium hydroxide / ethanol; water / 0.5 h / 60 °C / Inert atmosphere 4.2: 12 h / 60 °C / Inert atmosphere 5.1: toluene / 24 h / 120 °C 6.1: hydrogenchloride / ethanol / 1.5 h / 80 °C / Reflux 6.2: pH 14 View Scheme

1.1: N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; benzotriazol-1-ol / N,N-dimethyl-formamide / 12 h / 20 °C 2.1: sodium tetrahydroborate; acetic acid / 1,4-dioxane / 3.5 h / 10 - 105 °C 3.1: hydrogenchloride / water / 30 °C 3.2: 1 h / 0 - 20 °C 3.3: 1 h 4.1: sodium hydroxide / ethanol; water / 0.5 h / 60 °C / Inert atmosphere 4.2: 12 h / 60 °C / Inert atmosphere 5.1: toluene / 24 h / 120 °C 6.1: hydrogenchloride / ethanol / 1.5 h / 80 °C / Reflux 6.2: pH 14 View Scheme

1.1: sulfur / 7 h / 110 °C 2.1: sodium hydroxide; water / ethanol / 17 h / 80 °C 2.2: pH 2 3.1: N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; benzotriazol-1-ol / N,N-dimethyl-formamide / 12 h / 20 °C 4.1: sodium tetrahydroborate; acetic acid / 1,4-dioxane / 3.5 h / 10 - 105 °C 5.1: hydrogenchloride / water / 30 °C 5.2: 1 h / 0 - 20 °C 5.3: 1 h 6.1: sodium hydroxide / ethanol; water / 0.5 h / 60 °C / Inert atmosphere 6.2: 12 h / 60 °C / Inert atmosphere 7.1: toluene / 24 h / 120 °C 8.1: hydrogenchloride / ethanol / 1.5 h / 80 °C / Reflux 8.2: pH 14 View Scheme

1.1: sodium tetrahydroborate; acetic acid / 1,4-dioxane / 3.5 h / 10 - 105 °C 2.1: hydrogenchloride / water / 30 °C 2.2: 1 h / 0 - 20 °C 2.3: 1 h 3.1: sodium hydroxide / ethanol; water / 0.5 h / 60 °C / Inert atmosphere 3.2: 12 h / 60 °C / Inert atmosphere 4.1: toluene / 24 h / 120 °C 5.1: hydrogenchloride / ethanol / 1.5 h / 80 °C / Reflux 5.2: pH 14 View Scheme

1.1: hydrogenchloride / water / 30 °C 1.2: 1 h / 0 - 20 °C 1.3: 1 h 2.1: sodium hydroxide / ethanol; water / 0.5 h / 60 °C / Inert atmosphere 2.2: 12 h / 60 °C / Inert atmosphere 3.1: toluene / 24 h / 120 °C 4.1: hydrogenchloride / ethanol / 1.5 h / 80 °C / Reflux 4.2: pH 14 View Scheme