1: 97 percent / 3.0 M aq. HCl / ethyl acetate / 1 h / 25 °C 2: 53 percent / EDCI, HOBt*H2O / dimethylformamide / 12 h / 25 °C 3: aq. LiOH / tetrahydrofuran; methanol / 2 h / 25 °C 4: 3 N HCl / ethyl acetate / 1 h / 25 °C 5: 58 percent / NaHCO3, diphenyl phosphoroazidate (DPPA) / dimethylformamide / 72 h / 0 °C 6: 57 percent / BBr3 / CH2Cl2 / 3 h / -78 - 20 °C View Scheme

1.1: 96 percent / trifluoroacetic acid / CH2Cl2 / 1 h / 20 °C 2.1: 97 percent / PyBrOP; diisopropylethylamine / dimethylformamide / 0 - 20 °C 3.1: trifluoroacetic acid / 0.33 h / 20 °C 3.2: 63 percent / diisopropylethylamine; 1-hydroxybenzotriazole; 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride / CH2Cl2 / 24 h / 20 °C 4.1: 82 percent / LiOH*H2O / tetrahydrofuran; methanol; H2O / 1 h / 20 °C 5.1: HCl / ethyl acetate / 1 h 6.1: 2.5 mg / NaHCO3; diphenylphosphoryl azide / dimethylformamide / 72 h / 5 °C View Scheme