9-Bismatriptycene (BisTrip) Enables Single-Aryl Transfer for Regiospecific α-Arylation of Carbonyl Compounds

The α-arylation of carbonyl compounds is a cornerstone transformation in the synthesis of pharmaceuticals and natural products. Despite decades of effort using transition metal, main-group, and photoredox strategies, a general and practical α-arylation method with broad substrate scope has remained elusive. Here we show that 9-bismatriptycene (BisTrip), a rigid shackled form of triphenylbismuth, functions as a universal aryl group transporter, enabling controlled and regiospecific α-arylation across a wide range of ketones, including the construction of sterically demanding quaternary carbon centers as well as iodoarylation. BisTrip can be readily loaded with aryl groups from simple arylboronic acids in a one-pot procedure to give Aryl-BisTrip and is recovered in quantitative yield after aryl transfer to the carbonyl substrate. Significantly, the arylation of basic enolates proceeds at “warp speed”, reaching completion within seconds even at –78 °C, delivering record selectivity in a memory-of-chirality experiment. Computations support a low activation energy for the C–C bond-forming pathway that explains the preferential axial α-arylation observed in six-membered ring ketones. Collectively, these findings establish BisTrip as a powerful and broadly applicable platform with clear potential for complex molecule synthesis.