Atroposelective organocatalytic nucleophilic aromatic substitution for C–O bond construction

Abstract

The development of catalytic asymmetric strategies for directly constructing axially chiral diaryl ethers presents a substantial challenge owing to the inherent flexibility of the C–O bond and sterically congested substitution patterns that typically suppress both reactivity and enantioselectivity. Here we report an organocatalytic C–O bond-forming reaction that enables the facile synthesis of these chiral scaffolds. Employing a peptide-mimic phosphonium salt catalyst, this method exhibits broad substrate scope and achieves exceptional performance (up to 99% yield, 99% e.e.) under mild conditions. The efficacy of this methodology is further demonstrated through the late-stage diversification of complex molecular architectures, including derivatives of commercially available drugs. Mechanistic investigations delineate a peptide-mimic phosphonium salt-promoted stepwise nucleophilic aromatic substitution (SNAr) pathway, where the initial nucleophilic attack plays a pivotal role, serving as the determinant step for both rate and stereochemistry. Collectively, this work provides an efficient and enantioselective route to axially chiral diaryl ethers, opening practical avenues for integrating simple motifs into value-added, complex molecular architectures. Catalytic access to axially chiral diaryl ethers remains limited by the difficulty of enantioselective C–O bond formation. Now peptide-mimic phosphonium salts enable atroposelective nucleophilic aromatic substitution-driven C–O bond construction, affording axially enantioenriched diaryl ethers.