1: 1-but-3-ynyl-3,5-dimethyl-benzene With lithium hexamethyldisilazane in tetrahydrofuran T=-78°C; 2: With tBuOOLi in tetrahydrofuran; toluene T=-78 - 0°C; 2.5 h; 3: tri-isopropylsylil trifluoromethane sulfonate in tetrahydrofuran; toluene T=0°C; 0.5 h;

1.1: tetrahydrofuran / 3 h / Heating 2.1: NaOH / methanol; tetrahydrofuran; H2O 3.1: LiHMDS / tetrahydrofuran / -78 °C 3.2: lithium tert-butyl peroxide / tetrahydrofuran; toluene / 2.5 h / -78 - 0 °C 3.3: 93 percent / tetrahydrofuran; toluene / 0.5 h / 0 °C View Scheme