Formylation, dicyanovinylation and tricyanovinylation of 5-alkoxy- and 5-amino- substituted 2,2′-bithiophenes

Several donor–acceptor-substituted bithiophenes were synthesized by functionalization of the corresponding 5-alkoxy- or 5-aminobithiophenes by different methods: Vilsmeier formylation, metalation followed by reaction with DMF, direct tricyanovinylation reaction using TCNE or Knoevenagel condensation starting from the corresponding 5-formyl- derivatives of .