Efficient synthesis of thieno[3,2-b:4,5-b']diindoles and benzothieno[3,2-b]indoles by Pd-catalyzed site-selective C-C and C-N coupling reactions.

Heteroacenes (thieno[3,2-b:4,5-b']diindoles and benzothieno[3,2-b]indoles) were efficiently synthesized from tetrabromothiophene and 2,3-dibromobenzothiophene in two steps, respectively. In the first step, a site-selective Pd-catalyzed C-C coupling is carried out, followed by a two-fold C-N coupling with aromatic and aliphatic amines.