hydrogenchloride in 1,4-dioxane T=20°C; 1 h;

thionyl chloride T=0 - 20°C;

diethyl ether

1: 4-(N,N-dimethlyamino)pyridine; N-ethyl-N,N-diisopropylamine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 12 h / 20 °C 2: hydrogenchloride / 1,4-dioxane / 1 h / 20 °C View Scheme

1: 95 percent / dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBT), Et3N / dimethylformamide / 144 h / 5 °C 2: ethanol / 18 h / 20 °C View Scheme

1: 88.2 percent / HOBt; EDCI / dimethylformamide / 20 °C 2: 93.7 percent / aq. NaOH / methanol / 2 h / 20 °C View Scheme

1: 1) DCC, 2) NMM / 1) CH3CN, 0 deg C, 20 min, 2) 0 deg C, 1 h; r.t., overnight 2: 89 percent / acetic acid, H2 / Pd black View Scheme

triethylamine in tetrahydrofuran

1: 79 percent / Et3N, dicyclohexylcarbodiimide / CH2Cl2 / 0 deg C, 1 h -> room temperature, 15 h 2: 78 percent / H2 / Pd/C / ethanol; acetic acid / 15 h / 2068.6 Torr / Ambient temperature 3: 1.) aq. NaOH, aq. NaBH3CN, 2.) Dowex 50 (H+, 50-100 mesh) / 1.) water, room temperature, pH 7.0 View Scheme

1.1: NMM; isobutyl chloroformate / acetonitrile / 0.17 h / -15 °C 1.2: 1-hydroxybenzotriazole hydrate / acetonitrile / 0.17 h / cooling 1.3: 90.5 percent / NMM / acetonitrile; dimethylformamide / 20 °C / pH 8 2.1: HCl / dioxane / 1.5 h 3.1: 89.6 percent / NMM; isobutyl chloroformate / dimethylformamide; acetonitrile 4.1: HCl / dioxane / 1.5 h 5.1: 90.1 percent / NMM; isobutyl chloroformate / acetonitrile 6.1: ammonium formate / palladium on carbon / methanol / 0.5 h / 20 °C 7.1: trifluoroacetic acid View Scheme