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

The oxidative coupling reaction of nitrile-, methyl ester- andamino-functionalized 4-(alkylsulfanyl)-2,2′-bitiopheneswith FeCl 3 afforded symmetrical octithiophenes (OTs).These new OTs have solvatochromic properties similar to those reportedfor poly(w-functionalized alkylsulfanyl)thiophenes and have a potentialuse in optoelectronic devices. The carboxy-functionalized (obtainedthrough hydrolysis from nitrile and methyl ester functionalizedOTs) and the amino-functionalized OTs are also water-soluble astheir respective salts. From this and our previous results, theoxidative coupling with FeCl 3 can be proposed as a generalmethod for the synthesis of OTs when the starting materials are4-(alkylsulfanyl)-, 4-(w-functionalized alkylsulfanyl)-, and 4-alkylsulfanyl-4′-halo-2,2′-bithiophenes.