1: 74 percent / Amberlist A-21 / 16 h / Ambient temperature 2: 76 percent / pyridinium chlorochromate, 3 A molecular sieves / CH2Cl2 / 24 h / Ambient temperature 3: 97 percent / methanol / 10 h / Ambient temperature 4: 95 percent / LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C 5: 76 percent / BF3*(C2H5)2O, H2O / acetone / 10 h / Ambient temperature View Scheme

With  sodium nitrite in  N,N-dimethyl-formamide 7 h;  Ambient temperature;   

Multi-step reaction with 2 steps 1: 74 percent / Amberlist A-21 / 16 h / Ambient temperature2: 76 percent / pyridinium chlorochromate, 3 A molecular sieves / CH2Cl2 / 24 h / Ambient temperature  

Multi-step reaction with 3 steps 1: 74 percent / Amberlist A-21 / 16 h / Ambient temperature2: 76 percent / pyridinium chlorochromate, 3 A molecular sieves / CH2Cl2 / 24 h / Ambient temperature3: 97 percent / methanol / 10 h / Ambient temperature  

Multi-step reaction with 4 steps 1: 74 percent / Amberlist A-21 / 16 h / Ambient temperature2: 76 percent / pyridinium chlorochromate, 3 A molecular sieves / CH2Cl2 / 24 h / Ambient temperature3: 97 percent / methanol / 10 h / Ambient temperature4: 95 percent / LiAlH4 / tetrahydrofuran / 0.5 h / 0 °C