1: 81 percent / butyllithium / tetrahydrofuran; pentane / Ambient temperature 2: 74 percent / Li, NH3, ethanol / tetrahydrofuran / 0.5 h / -78 °C 3: 87 percent / glacial AcOH / 6 h / Ambient temperature 4: 92 percent / K2Os2(OH)4, (DHQD)2PHAL, K2CO3, potassium ferricyanate, CH3SO2NH2 / H2O; 2-methyl-propan-2-ol / 96 h / Ambient temperature 5: 1) CH3SO2Cl, pyridine, 2) K2CO3 / 1) CH2Cl2, RT, 2) aq. CH3OH, RT, 18 h View Scheme