1: 34 percent / Et3N, PhNCO / benzene / 1.) room temperature, 1 h, 2.) reflux, 1 h 2: 23 percent / acetic acid, Raney-Nickel, H2 / methanol; H2O / 3 h 3: BF3*Et2O, DMS / CH2Cl2 / 2.5 h / Ambient temperature 4: PTSA / benzene View Scheme