1: pyridine / dichloromethane / 20 °C / Inert atmosphere 2: triphenylphosphine; diethylazodicarboxylate / toluene / 20 °C / Inert atmosphere 3: sodium methylate / methanol / 5 h / 20 °C 4: pyridine / 5 h / 20 °C 5: 96 h / 55 °C 6: 10 wt Pd(OH)2 on carbon; hydrogen / ethanol; chloroform / 20 h / 20 °C View Scheme

1: 1.) TFAA, DMSO, 2.) Et3N / 1.) CH2Cl2, -78 deg C, 1.5 h, 2.) CH2Cl2, -78 deg C to r.t., 30 min 2: 77 percent / NaBH3CN, molecular sieves 3 Angstroem / methanol / 0.5 h / Ambient temperature 3: 91 percent / Li, NH3 / tetrahydrofuran / 2.5 h / -78 °C View Scheme

iodine; triphenylphosphine