1: 91 percent / NaHSO3; aq. H2O2; NaClO2 / acetonitrile / 6 h / 10 °C 2: (COCl)2; DMF / CH2Cl2 / 1.5 h / Heating 3: 293 mg / Et3N / CH2Cl2 / 0.5 h / 20 °C 4: 81 percent / Bu3P; 1,3-bis-(diphenylphosphino)propane; iPr2NEt / Pd(OAc)2 / dimethylformamide / 0.5 h / Heating View Scheme