A simple and efficient approach is developed for the synthesis of substituted 2,2'-bithiophene- and 2,2':5',2″-terthiophene-5-carboxylic acids and esters which is based on thiophene ring closure in the Fiesselmann reaction. Using this method, derivatives containing a long alkyl chain with or without an end functional group or an aryl substituent can be conveniently prepared.

The synthesis of bithiophene derivatives in three steps using Fiesselmann reaction for thiophene ring closure is developed.