Improved synthesis of N-alkyl substituted dithieno[3,2-b:2′,3′-d]pyrroles

A new, convergent and improved synthetic method to prepare N-alkyl substituted dithienopyrroles is described. The procedure consists of a Pd-catalyzed amination of 3,3′-dibromo-2,2′-bithiophene. The reaction conditions were optimized, which makes this method applicable to prepare these molecules easily in high yields and on a large scale.