Anchoring–migration strategy enables metal-free C2-selective cross-coupling of benzothiophenes

Abstract

Cross-coupling of (hetero)arenes offers a powerful means to access architecturally complex aromatics, but conventional approaches typically rely on transition-metal catalysis. Herein, we report a metal-free anchoring–migration strategy for the regioselective cross-coupling of benzothiophenes with diverse (hetero)arenes and 1,3-diketones. The process is initiated by an interrupted Pummerer-triggered electrophilic aromatic substitution that anchors the coupling partner to the polarity-inverted sulfur center of benzothiophene, followed by a thermodynamically driven neighboring-site migration through a transient dearomatization pathway. The protocol features broad substrate scope, operational simplicity, and excellent regioselectivity. Furthermore, a downstream photochemical intramolecular 6π-electrocyclization enables a one-pot formal [4 + 2] annulation with coumarin derivatives, providing streamlined access to polycyclic benzothiophene frameworks. This conceptually distinct strategy offers a general metal-free approach for densely functionalized benzothiophenes.