Modular bismacycles for the selective C–H arylation of phenols and naphthols

Given the important role played by 2-hydroxybiaryls in organic, medicinal and materials chemistry, concise methods for the synthesis of this common motif are extremely valuable. In seeking to extend the lexicon of synthetic chemists in this regard, we have developed an expedient and general strategy for the ortho -arylation of phenols and naphthols using readily available boronic acids. Our methodology relies on in situ generation of a uniquely reactive Bi( v ) arylating agent from a bench-stable Bi( iii ) precursor via telescoped B–to–Bi transmetallation and oxidation. By exploiting reactivity that is orthogonal to conventional metal-catalysed manifolds, diverse aryl and heteroaryl partners can be rapidly coupled to phenols and naphthols under mild conditions. Following arylation, high-yielding recovery of the Bi( iii ) precursor allows for its efficient re-use in subsequent reactions. Mechanistic interrogation of each key step of the methodology informs its practical application and provides fundamental insight into the underexploited reactivity of organobismuth compounds. Step-economic access to the biologically relevant 2-hydroxybiaryl motif represents a long-standing challenge in synthetic organic chemistry. Now, a bismuth-mediated oxidative arylation of phenols and naphthols with boronic acids has been developed — supported by experimental mechanistic insight — giving a direct and practical route to this valuable molecular architecture.