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

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

1: With acetic acid T=70°C; 2 h; 2: With methanol; sodium methylate in dichloromethane T=40°C; Further stages.;