1: 76 percent / (PhO)2P(O)N3, PPh3, EtO2CN=NCO2Et / tetrahydrofuran / 1 h / 23 °C 2: benzene / 26 h / Heating 3: tBuNH2, KN(TMS)2 4: 1.) BH3, 2.) NaOAc, H2O2 / 1.) THF, 23 deg C, 10 h, 2.) CH3OH, 23 deg C, 12 h 5: 85 percent / 6 N HCl / tetrahydrofuran / 12 h / 23 °C View Scheme