1: 89 percent / Et3N / tetrahydrofuran / 0.25 h 2: 90 percent / LiOH / H2O; dioxane / 18 h / Ambient temperature 3: 1.) 1-hydroxybenzotriazole hydrate, N,N'-dicyclohexylcarbodiimide / 1.) EtOAc, RT, 2 h, 2.) 18 h 4: 89 percent / H2 / Pearlman's catalyst / ethanol / 18 h / 25 °C / 2327.2 Torr 5: 80 percent / ethyl acetate / 24 h / Ambient temperature View Scheme

pyridine in dichloromethane 2 h; Ambient temperature;

pyridine in dichloromethane; toluene T=-20 - 20°C;

pyridine in dichloromethane; ethyl acetate