Octithiophenes via One-Pot Oxidative Coupling of 4-(ω-Functionalized Alkylsulfanyl)-2,2′-Bithiophenes

The oxidative coupling reaction with FeCl3 on nitrile, methyl ester and amino functionalized 4-(alkylsulfanyl)-2,2’-bitiophenes afforded symmetric octithiophenes (OTs). These new OTs have solvatochromic properties similar to those reported for poly(ω-functionalized alkylsulfanyl)thiophenes and have a potential use in optoelectronic devices. The carboxy (obtained through hydrolysis from nitrile and methyl ester functionalized OTs) and the amino functionalized OTs are also water soluble as salts. From this and our previous results, the oxidative coupling with FeCl3 can be proposed as a general method for the synthesis of OTs when the starting materials are 4-(alkylsulfanyl)-, 4-(ω-functionalized alkylsulfanyl)-, and 4-alkylsulfanyl-4’-halo-2,2’-bithiophenes.