1: 78 percent / N-bromosuccinimide / acetonitrile; H2O / 0.5 h / 60 °C 2: 4.23 g / t-BuOK / 2-methyl-propan-2-ol; tetrahydrofuran / 0 deg C, 2h, then room temp., 1h 3: DBU / toluene / 0 deg C, 2h, then room temp., 30 min. 4: 99 percent / (Me2N)3P, CCl4 / tetrahydrofuran / -78 deg C -> room temp. (3h) View Scheme

Multi-step reaction with 6 steps 1: 8 percent / trimethylsilyl triflate / 1,2-dichloro-ethane / 0.5 h / 0 °C2: 88 percent / diethylaminosulfur trifluoride / toluene; 1,2-dichloro-ethane / 40 °C3: 42 percent / n-Bu3SnOTf, molecular sieves 4 A / CCl4 / 16 h / Ambient temperature4: 82 percent / n-Bu3SuH, AIBN / toluene5: H2 / Pd/C / methanol6: DMAP, pyridine