1: 100 percent / 4A molecular sieves; BF3*OEt2 / CH2Cl2 / 1 h / -40 °C 2: 80 percent / TsOH*H2O / methanol; CH2Cl2 / 2 h / 20 °C 3: 75 percent / pyridine / CH2Cl2 / -20 °C 4: 93 percent / 4A molecular sieves; BF3*OEt2 / CH2Cl2 / 0.5 h / 0 °C 5: 85 percent / NaOH; H2O / tetrahydrofuran / 45 °C View Scheme

1: 100 percent / 4A molecular sieves; BF3*OEt2 / CH2Cl2 / 1 h / -40 °C 2: 80 percent / TsOH*H2O / methanol; CH2Cl2 / 2 h / 20 °C 3: 75 percent / pyridine / CH2Cl2 / -20 °C 4: 89 percent / 4A molecular sieves; BF3*OEt2 / CH2Cl2 / 1 h / -40 °C 5: 100 percent / NaOH; water / methanol; tetrahydrofuran / 5 h / 45 °C View Scheme

indium(III) chloride in dichloromethane T=16°C; 6 h;

Multi-step reaction with 2 steps 1: n-BuNH2 / tetrahydrofuran / 8 h / 25 °C2: DBU / CH2Cl2 / 0.5 h / 0 °C