caesium carbonate in ethyl acetate; acetonitrile

sulfuric acid in ethanol

diphenylphosphoranyl azide; triethylamine in toluene T=100°C; 4 h;

1: DIBAL / tetrahydrofuran / 18 h / 0 - 20 °C 2: ZnCl2, SOCl2 / dioxane / 0.67 h View Scheme

1: thionyl chloride / 16 h / 70 °C 2: ammonia / dichloromethane; methanol / 3 h / 20 °C 3: trifluoroacetic anhydride; pyridine / 1,4-dioxane / 3 h / 0 - 20 °C View Scheme

1.1: benzotriazol-1-ol; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; N-ethyl-N,N-diisopropylamine / tetrahydrofuran; N,N-dimethyl-formamide / 18 h / 0 - 20 °C / Inert atmosphere 2.1: 2-(trifluoromethyl)phenyllithium / tetrahydrofuran; hexane / 0.83 h / -65 - -55 °C / Inert atmosphere 2.2: 1.5 h / -65 °C / Inert atmosphere 2.3: Inert atmosphere View Scheme

copper(l) iodide; copper(l) chloride in N,N-dimethyl-formamide 4 h; Inert atmosphereReflux;

1.1: N,N-dimethyl-formamide; thionyl chloride / toluene / 1 h / 45 - 50 °C 1.2: 1 h / 10 - 25 °C 2.1: n-butyllithium; Di-n-butylmagnesium / hexane; tetrahydrofuran / 1.5 h / -11 - 20 °C / Inert atmosphere 2.2: 7.5 h / -11 °C 3.1: manganese(IV) oxide / isobutyramide / 60 h / 25 °C / Inert atmosphere 4.1: pyridine; cinchonine / tetrahydrofuran / 1.75 h / -25 °C / Inert atmosphere 5.1: calcium chloride; sodium tetrahydroborate / ethanol; tetrahydrofuran / 8.5 h / -7 - 5 °C 5.2: 5 °C View Scheme