Rh( iii )-catalyzed heteroannular-selective heteroarylation of biaryls: facile access to heteroacenes with sulfur-embedded 5–7 ring topology

Acenes with non-benzenoid 5-7 ring topology have drawn significant attention. Nevertheless, introducing sulfur atoms into 5/7-membered rings of acenes has not yet been achieved owing to synthetic challenges. Disclosed herein is a rhodium-catalyzed heteroannular-selective C-H/C-H oxidative cross-coupling reaction of 2-substituted biaryls with heteroarenes, which provides a convenient approach to heteroacenes with sulfur-embedded 5-7 ring topology. This protocol demonstrates excellent regioselectivity and broad functional group tolerance, enabling the efficient synthesis of a diverse library of thioether- and seleno-ether-substituted biheteroaryl compounds. Heteroacenes featuring sulfur-embedded 5-7 or 5-6 ring topologies can be switchably constructed through further intramolecular cyclization involving directing groups. Crystal structure analysis, along with studies on photophysical properties and aromaticity, indicates that heteroacenes with sulfur-embedded 5-7 ring topology have the potential as high-performance organic semiconductor materials.