1: With tetra-N-butylammonium borohydride in dichloromethane 16 h; Inert atmosphereReflux; 2: With hydrogenchloride in water 0.333333 h; Reflux; 3: With sodium carbonate in water Cooling; Product distribution / selectivity;

sodium T=100°C; 7 h;

1.1: sodium hydride / ethyl acetate; N,N-dimethyl-formamide; toluene / 10 h / 80 °C 1.2: 2 h / 110 °C 1.3: pH 9 2.1: sulfur / ethyl acetate; water / 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 / 1,4-dioxane / 0.17 h / 10 °C 5.2: 3.5 h / 10 - 105 °C 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 / 1,4-dioxane / 0.17 h / 10 °C 2.2: 3.5 h / 10 - 105 °C View Scheme

1.1: sulfur / ethyl acetate; water / 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 / 1,4-dioxane / 0.17 h / 10 °C 4.2: 3.5 h / 10 - 105 °C View Scheme

1.1: sodium hydroxide; water / ethanol / 17 h / 80 °C 1.2: pH 2 2.1: N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; benzotriazol-1-ol / N,N-dimethyl-formamide / 12 h / 20 °C 3.1: sodium tetrahydroborate / 1,4-dioxane / 0.17 h / 10 °C 3.2: 3.5 h / 10 - 105 °C View Scheme

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: sodium tetrahydroborate; acetic acid / 1,4-dioxane / 3.5 h / 10 - 105 °C 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

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 View Scheme