Thiophenes and Their Benzo Derivatives: Reactivity

Catalytic Oxidative C–H Annulation of Arylthiol Derivatives with 1,3-Diynes toward 3,3′-Bibenzothiophenes

“…Bithiophene derivatives have wide applications in the fields of organic functional materials, such as organic thermoelectrics (OTEs), organic field-effect transistors (OFETs), organic solar cells (OSCs), and organic light-emitting diodes (OLEDs), because of their unique optical and electrical properties . Among the diverse methods to assemble such structures, transition-metal-catalyzed C–X/C–M coupling reactions between two preactivated thiophene units represent the most common conventional approach. , Recently, direct C–H functionalization has offered a more straightforward synthetic route that does not require the prefunctionalization of coupling partners (Scheme a) . Despite significant progress, these methods still suffer from disadvantages such as uneasily available (benzo)­thiophene substrates, poor selectivity in the cross-coupling toward nonsymmetrical bithiophenes, and low reactivities of substrates with steric and electronic limitations.…”