1: 95 percent / DCC, 4-pyrrolidinopyrridine / CH2Cl2 / 5 h / 25 °C 2: 86 percent / DCC, 4-pyrrolidinopyrridine / CH2Cl2 / 5 h / 25 °C 3: Bu4NF / tetrahydrofuran / 3 h / 25 °C 4: Ph3P, EtOsCN=NCO2Et / 20 h / 25 °C 5: 70 percent / MeOH / NaOMe / 2 h / 0 °C View Scheme