in ethylene glycol dimethyl ether; toluene T=-50°C;

1: 80 percent / tetrahydrofuran / 1 h 2: 81 percent / tetrahydrofuran; toluene / -78 deg C, 5 min; RT, 12 h 3: 99 percent / HBr / tetrahydrofuran / -80 °C 4: 62 percent / 1,2-dimethoxy-ethane; toluene / -50 °C View Scheme

1: t-BuOK / 1,2-dimethoxy-ethane 2: 81 percent / tetrahydrofuran; toluene / -78 deg C, 5 min; RT, 12 h 3: 99 percent / HBr / tetrahydrofuran / -80 °C 4: 62 percent / 1,2-dimethoxy-ethane; toluene / -50 °C View Scheme

aluminium trichloride 1.) C6H6, reflux, 12 h, 2.) THF, reflux, 5 h; Yield given. Multistep reaction. Yields of byproduct given;

1: 99 percent / HBr / tetrahydrofuran / -80 °C 2: 62 percent / 1,2-dimethoxy-ethane; toluene / -50 °C View Scheme