1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride; N-ethyl-N,N-diisopropylamine in dichloromethane T=20°C; Inert atmosphere;

potassium carbonate in N,N-dimethyl-formamide T=20°C; 3 h;

1.1: 1,1'-carbonyldiimidazole / tetrahydrofuran / 1 h / Cooling with ice 1.2: 20 °C / Cooling with ice 2.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C / Inert atmosphere 2.2: -78 - 20 °C / Inert atmosphere 3.1: R-CBS-oxazaborolidine / tetrahydrofuran; toluene / -15 °C / Inert atmosphere 3.2: -15 °C / Inert atmosphere View Scheme

1.1: 1,1'-carbonyldiimidazole / tetrahydrofuran / 1 h / Cooling with ice 1.2: 20 °C / Cooling with ice 2.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -78 °C / Inert atmosphere 2.2: -78 - 20 °C / Inert atmosphere 3.1: R-CBS-oxazaborolidine / tetrahydrofuran; toluene / -15 °C / Inert atmosphere 3.2: -15 °C / Inert atmosphere 4.1: sodium hydride / N,N-dimethyl-formamide; mineral oil / 0 - 20 °C 4.2: 0 - 20 °C 5.1: sodium tetrahydroborate / methanol / 20 °C 6.1: triethylamine / dichloromethane / 3 h / -5 - 20 °C 7.1: sodium azide / N,N-dimethyl-formamide / 16 h / 80 °C 8.1: water; triphenylphosphine / tetrahydrofuran / 16 h / 20 °C 9.1: 4-(N,N-dimethlyamino)pyridine; triethylamine / dichloromethane / 0 - 5 °C View Scheme