1: 96.1 percent / acetic acid; tetrahydrofuran; H2O / 50 °C 2: 90 percent / pyridine / Ambient temperature 3: 80.4 percent / trimethylsilyl triflate / CH2Cl2 / 0 °C 4: 93.1 percent / K2CO3 / methanol; H2O 5: n-BuLi / 1) ether - HMPA, 2) ether 6: LiBr 7: t-BuLi / tetrahydrofuran; hexamethylphosphoric acid triamide / -78 °C 8: 63.2 percent / N-chloro-succinimide 9: 50 percent / DBU / tetrahydrofuran / 4 h / Heating 10: C2H5MgBr View Scheme