1: 93 percent / 4A molecular sieves; BF3*OEt2 / CH2Cl2 / 0.5 h / 0 °C 2: 85 percent / NaOH; H2O / tetrahydrofuran / 45 °C View Scheme

1: 89 percent / 4A molecular sieves; BF3*OEt2 / CH2Cl2 / 1 h / -40 °C 2: 100 percent / NaOH; water / methanol; tetrahydrofuran / 5 h / 45 °C View Scheme