Iron-catalyzed selective oxidative arylation of phenols and biphenols

The single-step synthesis of protected fucols and unnatural polyaryls by biomimetic oxidative cross-coupling between phenolic components and 1,3,5-trimethoxybenzene catalyzed by FeCl₃ in fluorinated solvents is reported. The regioselectivity (ortho, meta or para) and the chemoselectivity (C[sbnd]C vs C[sbnd]O) in this highly efficient transformation are controlled by the phenolic ortho-groups of the growing phenolic oligomer. The reaction scope was examined by coupling biphenol derivatives with the nucleophilic arene to afford large polyaryl compounds that are not easily accessible by other means. The versatility of the catalytic system in designing polyaryl frameworks was demonstrated by performing a sequential oxidative phenol-phenol and phenol-arene coupling reaction that afforded a single polyaryl product in high efficiency.