1.1: LiHMDS / tetrahydrofuran / -78 °C 1.2: lithium tert-butyl peroxide / tetrahydrofuran; toluene / 2.5 h / -78 - 0 °C 1.3: 80 percent / tetrahydrofuran; toluene / -78 - 0 °C 2.1: 88 percent / trifluoromethanesulfonimide / CH2Cl2 / 1 h / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; petroleum ether / 1.5 h / 20 °C 1.2: MgBr2 / tetrahydrofuran; petroleum ether / 0.5 h / 20 °C 1.3: tetrahydrofuran; petroleum ether / 20 °C 2.1: aq. NaOH / methanol; tetrahydrofuran View Scheme

1: 2-methyl-4-propyl-hex-1-en-5-yne 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=-78 - 0°C;