1: 83 percent / (i-Pr)2NEt / propan-2-ol / 3.5 h 2: aq. LiOH / 1,2-dimethoxy-ethane / 0.5 h 3: imidazole / 1,2-dimethoxy-ethane / 20 h / 0 - 20 °C 4: 92 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h / 0 - 20 °C 5: 69 percent / 8N HCl / propan-2-ol / 6 h / Ambient temperature View Scheme

1: 83 percent / (i-Pr)2NEt / propan-2-ol / 3.5 h 2: aq. LiOH / 1,2-dimethoxy-ethane / 0.5 h 3: imidazole / 1,2-dimethoxy-ethane / 20 h / 0 - 20 °C 4: 92 percent / 1-ethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, HOBt, Et3N / dimethylformamide / 18 h / 0 - 20 °C 5: 69 percent / 8N HCl / propan-2-ol / 6 h / Ambient temperature 6: 76 percent / Et3N / dimethylformamide / 12 h View Scheme