1: With n-butyllithium in diethyl ether T=-70°C; Metallation; 2: With (PhSO2)2S in diethyl ether T=-70 - 0°C; Etherification;

1: 2,5-dimethyl-3,4-dibromothiophene With n-butyllithium; (PhSO2)2S in diethyl ether T=-78°C; Metallation; 45 h; 2: 3,4-Dibromo-thiophene in hexane T=-78°C; Substitution; 2 h;

1: 3,4-dibromo-2,5-dioctylthiophene With n-butyllithium; (PhSO2)2S in diethyl ether T=-78°C; Metallation; 45 h; 2: 3,4-Dibromo-thiophene in hexane T=-78°C; Substitution; 2 h;

1.1: 15 percent / Br2 / CHCl3 / 4 h / 0 °C 2.1: n-BuLi; S(SO2Ph)2 / diethyl ether / 45 h / -78 °C 2.2: 4.6 g / hexane / 2 h / -78 °C View Scheme

1.1: 100 percent / AlCl3 / benzene / 0 - 20 °C 2.1: 44 percent / 85 percent N2H4*H2O; NaOH / bis-(2-hydroxy-ethyl) ether / 3 h / Heating 3.1: 44 percent / Br2 / CHCl3 / 4 h / 0 °C 4.1: n-BuLi; S(SO2Ph)2 / diethyl ether / 45 h / -78 °C 4.2: 3.6 g / hexane / 2 h / -78 °C View Scheme

1.1: 56 percent / 85 percent N2H4*H2O; NaOH / bis-(2-hydroxy-ethyl) ether / 4 h / Heating 2.1: 100 percent / AlCl3 / benzene / 0 - 20 °C 3.1: 44 percent / 85 percent N2H4*H2O; NaOH / bis-(2-hydroxy-ethyl) ether / 3 h / Heating 4.1: 44 percent / Br2 / CHCl3 / 4 h / 0 °C 5.1: n-BuLi; S(SO2Ph)2 / diethyl ether / 45 h / -78 °C 5.2: 3.6 g / hexane / 2 h / -78 °C View Scheme