1: fluoro-1 methoxymethylenoxy-2 benzene With n-butyllithium in tetrahydrofuran; hexane T=0°C; 1.5 h; 2: carbon dioxide in tetrahydrofuran; hexane T=-78°C; 1.5 h; 3: With hydrogenchloride in tetrahydrofuran; hexane T=20°C;

1: 79 percent / butyllithium / hexane; tetrahydrofuran / 6 h / -75 °C 2: 72 percent / boron trifluoride-diethyl ether / methanol / 15 h / 25 °C View Scheme

1.1: n-butyllithium / hexane; diethyl ether / 3 h / 0 - 20 °C / |Inert atmosphere 1.2: 0.17 h / 0 °C / |Inert atmosphere 1.3: |Inert atmosphere 2.1: montmorillonite K-10 / benzene / 24 h / |Reflux View Scheme

1: 84 percent / butyllithium; potassium tert-butoxide / hexane; tetrahydrofuran / 2 h / -75 °C 2: 83 percent / boron trifluoride-diethyl ether / methanol / 15 h / 25 °C View Scheme

1: 1.) n-BuLi / 1.) THF, hexane, -78 deg c, 2.5 h, 2.) THF, hexane, RT, 24 h 2: 46 percent / aq. HCl / tetrahydrofuran / 6 h / 60 °C View Scheme