1: 70 percent / pyridinium chlorochromate, A4 molecular sieves / CH2Cl2 / 24 h / Ambient temperature 2: 78 percent / AIBN, tri n-butyltin hydride / benzene / 5 h / Heating 3: 71 percent / boron trifluoride etherate, p-toluenesulfonic acid / acetone; H2O / Ambient temperature 4: 72 percent / sodium methoxide / methanol View Scheme