1: 3-bromo-2-ethyl-5-(ethylthio)thiophene With n-butyllithium in diethyl ether; hexane T=-70°C; 2: 1,2,3,3,4,4,5,5-octafluorocyclopentene in diethyl ether; hexane T=-70 - 20°C; 2 h;

Multi-step reaction with 2 steps 1.1: 40 percent / Br2 / acetic acid / 5 h / 2 - 20 °C2.1: n-BuLi / diethyl ether / 0.17 h / -70 °C2.2: 75 percent / diethyl ether / 14 h / -70 - 20 °C