1: 73.9 percent / 1-<3-(dimethylamino)propyl>-3-ethylcarbodiimide hydrochloride, 1-hydroxybenzotriazole, Et3N / dimethylformamide / 20 h / Ambient temperature 2: 91 percent / HCl / dioxane / 2 h / Ambient temperature 3: 72 percent / 1-<3-(dimethylamino)propyl>-3-ethylcarbodiimide hydrochloride, 1-hydroxybenzotriazole, Et3N / dimethylformamide / 24 h / Ambient temperature 4: 96 percent / HCl / dioxane / 2 h / Ambient temperature 5: 13.5 percent / Et3N / CH2Cl2 / 1.) -60 deg C, 30 min, 2.) 10 deg C, 1 h 6: 14 percent / m-CPBA / CH2Cl2 / 48 h / Ambient temperature View Scheme