1: 85 percent / p-toluenesulfonic acid 2: 92 percent / tetrahydrofuran / 1 h / -78 °C 3: 60 percent Turnov. / diethyl ether / 84 h / -24 °C 4: hydrogen / 10percent Pd(C) / aq. ethanol 5: 63 percent / DIBAL-H / 1.) -40 deg C, 1.0 h, 2.) 0 deg C, 0.5 h 6: 71 percent / Et3N, 4-N,N-dimethylaminopyridine View Scheme