Synthesis of benzoditiophene based atropoisomer through Pd-catalyzed cross coupling reactions

The biaryl motif occupies an iconic role in chemistry, being a key structural feature of natural products, biologically active molecules, drugs, agrochemicals, and other novel optical and mechanical materials. Furthermore, the stereogenic axes provide rigid molecular frameworks for highly efficient tools in asymmetric synthesis.1 Exploiting the experience acquired in our laboratories on the synthesis of compounds based on alternating thiophene and benzene rings2, we have started the study of a simple and efficient synthetic route to prepare bis(benzoditiophenes) system 2, through Pd-catalysed cross coupling reactions, starting from bromide 1. This strategy provides a convenient approach to an interesting class of chiral atropisomeric biaryl derivatives with C2-symmetry, which are expected to have broad applications in asymmetric reactions, including the enantioselective synthesis of tetrathiahelicene derivatives.