1.1: imidazole / dimethylformamide / 20 °C 2.1: tetrahydrofuran / 2.5 h / -78 °C 2.2: Et3SiH / acetonitrile / -40 °C View Scheme

1: tetrahydrofuran / 1 h / -78 °C 2: BF3*Et2O; Et3SiH / CH2Cl2 / -78 - 20 °C View Scheme

1.1: sodium hydride / ethylene glycol dimethyl ether / 0.5 h / 20 °C 1.2: 2 h / -10 °C 2.1: lithium hexamethyldisilazane / tetrahydrofuran / 0.5 h / -78 °C 2.2: 4 h / -78 °C 3.1: pyridinium p-toluenesulfonate; methanol / 2 h / |Reflux 4.1: toluene / 1 h / |Reflux 5.1: phosphorous acid trimethyl ester / 48 h / |Reflux 6.1: tetrahydrofuran / 1 h / 20 °C 7.1: Grubb's 2nd generation catalyst / dichloromethane / 8 h / 20 °C 8.1: lithium aluminium tetrahydride / tetrahydrofuran / 1 h / 20 °C / |Reflux 9.1: toluene / 4 h / |Reflux 10.1: hydrogen / ethanol / 10 h / 20 °C View Scheme