1: 40 percent / 1) CBr4; / 2) CH3CN 2: LiHMDS / tetrahydrofuran; hexamethylphosphoric acid triamide / -78 °C 3: -78 - -45 °C 4: 80 percent / (nBu)4NF / tetrahydrofuran / 0 - 25 °C 5: 70 percent / LiOH / 1,2-dimethoxy-ethane; H2O / Ambient temperature View Scheme