1: 77 percent / thionyl chloride / CH2Cl2 / 24 h 2: 76 percent / KOBt / CH2Cl2 / 0.5 h / Ambient temperature 3: 83 percent / aq. NaOH / methanol / 3 h 4: 77 percent / SOCl2 / CH2Cl2 / 24 h / Ambient temperature 5: 62 percent / KOBt / CH2Cl2 / Ambient temperature 6: 57 percent / aq. HCOOH / Pd black View Scheme