1.1: dibutylboron triflate; diisopropylethylamine / CH2Cl2 / 0.5 h / -78 °C 1.2: CH2Cl2 / 3 h / -78 - 20 °C 2.1: 12 mg / pyridine; chromium trioxide / CH2Cl2 / 0.33 h / 20 °C 3.1: 85 percent / HF / H2O; acetonitrile / 3 h / 20 °C 4.1: LiOH / H2O; 1,2-dimethoxy-ethane / 7 h / 80 °C View Scheme