Synthesis of [1]Benzothieno[3,2-b][1]benzothiophenes through Iodine-Mediated Sulfur Insertion Reaction

[1]Benzothieno[3,2-b][1]benzothiophenes (BTBTs) are important molecules that have been extensively studied as high-performance organic field-effect transistors (OFETs). Therefore, it is important to develop a simple synthetic method for these molecules. In this paper, a synthetic method to obtain the BTBTs from 2-arylbenzo[b]thiophenes and elemental sulfur, in which two C-S bonds are formed at once, is described. In this method, molecular iodine plays a very important role as an additive. The role of iodine is discussed in the presumed reaction pathways.