1: With ethylaluminum dichloride in diethyl ether; hexane T=-45 - -30°C; 2 h; 2: With hydrogen fluoride in acetonitrile T=50°C; 4 h; Further stages.;

1.1: NaH / tetrahydrofuran / 0 °C 1.2: 85 percent / tetrahydrofuran / 2 h 2.1: p-TsOH / methanol / 0.5 h / 20 °C 2.2: 76 percent / benzene / 1 h / 20 °C View Scheme