1: potassium carbonate / N,N-dimethyl-formamide / 100 °C 2: acetic acid; N-bromosuccinmide / 5 h / 10 - 20 °C 3: trifluoroacetic acid / dichloromethane / 2 h / 10 - 20 °C 4: triethylamine; benzotriazol-1-ol; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / tetrahydrofuran; N,N-dimethyl-formamide / 10 h / 20 °C View Scheme

sodium bis(2-methoxyethoxy)aluminium dihydride in benzene T=5 - 10°C; 0.75 h;

hydrogenchloride; hydrogen sulfide in tetrahydrofuran

magnesium in tetrahydrofuran 1.) reflux, 30 min, 2.) -45 deg C, 1.5 h; room temperature, 1.5 h;

1: With sulfur in tetrahydrofuran; toluene T=0 - 20°C; 2: With hydrogenchloride in tetrahydrofuran; water; toluene

1: 80 percent / acetic acid / 1 h / Ambient temperature 2: 84 percent / sodium bis(methoxyethoxy)aluminum dihydride / benzene / 0.75 h / 5 - 10 °C View Scheme

1.1: hydrogenchloride; sodium nitrite / water / 0.25 h / Cooling with ice 1.2: 0.33 h / 20 °C 2.1: Na2S*9H2O; trichloroacetic acid / ethyl acetate / 0.58 h / Reflux; Inert atmosphere View Scheme

Na2S*9H2O; trichloroacetic acid in ethyl acetate 0.583333 h; RefluxInert atmosphere;

Na2S*9H2O; trichloroacetic acid in ethyl acetate 0.666667 h; RefluxInert atmosphere;