1: 96 percent / Et3N / CH2Cl2 / 2 h / 0 °C 2: 95 percent / p-acetamidobenzenesulfonyl azide, DBU / acetonitrile / 3 h / 0 °C 3: 83 percent / Rh2(S-PTTL)4 / CH2Cl2 / 6 h / 23 °C 5: 74 percent / 6N HCl / H2O / 6 h / Heating View Scheme