Effective synthesis of regular ladder-type oligo(p-phenol)s via intramolecular SNAr O-arylation reaction

A series of novel ladder-type O-heteroarenes containing benzofuran units were effectively synthesized from the precursors via intramolecular SNAr reaction between F and OH groups in the backbone. The key intramolecular SNAr reaction was catalyst-free and highly efficient, moreover, the accurate annulation of fluorine atom ensured the regularity of the structure. We could smoothly obtain the ladder-type oligomer with seven oxygen bridges. The successes of the ladder-type oligomers also demonstrated the feasibility for preparing other regular oligomers and polymers with oxygen bridges.