1: 1.9 g / trifluoroacetic acid / CH2Cl2 / 1 h 2: diisopropylethylamine, diethylphosphoryl cyanide / CH2Cl2 / 18 h 3: 100 percent / 1-hydroxybenzotriazole / methanol / 18 h 4: 72 percent / diisopropylethylamine / CH2Cl2 / 18 h 5: 100 percent / diisopropylethylamine / CH2Cl2 / 1.25 h 6: 78 percent / 4-(dimethylamino)pyridine, benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate / CH2Cl2 / 120 h 7: 100 percent / ammonium formate / 5percent Pd/C / dimethylformamide / 18 h View Scheme