Synthesis and Structural Analysis of 3,6-Diarylthieno[3,2-b]thiophenes by Site-selective Pd-catalyzed C-H Functionalization

Thieno[3,2-b]thiophene represents a typical core structure in a large number of organic optoelectronic materials and molecular magnetism. One-pot efficient approach to modify the electronic structure of thieno[3,2-b]thiophene is to introduce suitable substituents into this π- conjugated skeleton. In this paper, we report on a facile route to precisely functionalize thieno[3,2- b]thiophene by the direct Pd-catalyzed arylation reaction with boronic acids. Based on this procedure, a number of 3,6-diarylthieno[3,2-b]thiophenes were prepared in good yields. NMR methods and XRay crystal structure analysis confirmed high regioselectivities at the C-3 and C-6 positions of thieno[3,2-b]thiophene skeleton.