1: H2 / Lindlar's catalyst / methanol / 20 °C 2: 80 percent / MnO2 / hexane / 0.5 h View Scheme

1: 1.) ethylmagnesium bromide, 2.) cuprous bromide / 1) THF, 60 deg C, 45 min; 2) room temperature, 10 min; 3) THF, 60 deg C, 45 min 2: 103.5 g / aq. sulfuric acid / acetone / 3 h / Ambient temperature View Scheme

1: 1.) ethylmagnesium bromide, 2.) cuprous bromide / 1) THF, 60 deg C, 45 min; 2) room temperature, 10 min; 3) THF, 60 deg C, 45 min 2: 103.5 g / aq. sulfuric acid / acetone / 3 h / Ambient temperature View Scheme

sulfuric acid in acetone T=20°C; 3 h;

1.1: 67 percent / PBr3; pyridine / diethyl ether / 2 h / 20 °C 2.1: EtMgBr; CuCl / diethyl ether / 2 h / 20 °C 2.2: 28 percent / diethyl ether / 24 h / Heating View Scheme

1: 98 percent / p-toluenesulfonic acid / diethyl ether / 0.33 h / Ambient temperature 2: 1.) ethylmagnesium bromide, 2.) cuprous bromide / 1) THF, 60 deg C, 45 min; 2) room temperature, 10 min; 3) THF, 60 deg C, 45 min 3: 103.5 g / aq. sulfuric acid / acetone / 3 h / Ambient temperature View Scheme

1: 2-trans-penten-4-yn-1-ol With ethylmagnesium bromide; copper(l) chloride in diethyl ether T=20°C; 2 h; 2: 1-bromooct-2-yne in diethyl ether 24 h; Heating;

hydrogen; Lindlar's catalyst in methanol T=20°C;