1: ethyl bromide With magnesium in tetrahydrofuran T=50 - 60°C; Heating / reflux; 2: cyclopropyl acetylene in tetrahydrofuran; toluene T=20°C; 1.5 h; 3: With trimethyl orthoformate in tetrahydrofuran; toluene T=100 - 120°C; 4 h;

2-{2-(2-hydroxyethyl)thioethyl}thioethanol; hydrogen; Lindlar's catalyst in ethyl acetate P=750.075 Torr; 2.5 h;