1: 90 percent 2: 83 percent / H2O / acetonitrile / 0 °C 3: 91 percent / tri-n-butyltin hydride; 2,2'-azobisisoburtyronitrile / toluene / 2 h / 95 °C 4: 100 percent / tetra-n-butylammonium fluoride / tetrahydrofuran / 0 °C 5: 100 percent / aq. ammonia / methanol View Scheme