Ion-Pair Receptors Couple Cation Binding with Molecular Electron Storage for Room-Temperature Birch-Type Reduction

Abstract The Birch reduction provides a powerful route to partially dearomatized products from aromatic precursors, but classical protocols rely on highly reactive solvated electrons generated from alkali metals in cryogenic liquid ammonia, offering limited molecular control over reducing equivalents. Here we show that ion-pair receptors couple Na+ binding with molecular electron storage within electron-deficient diimide-based π-frameworks. Reduction with sodium generates persistent sodium-associated radical-anion ion pairs in which the unpaired electron is delocalized predominantly over the π-accepting framework. Time-dependent UV–vis and EPR measurements establish persistence of the representative Na+·IP-4•– state in THF at room temperature under an inert atmosphere. Control experiments show that covalent integration of the Na+-binding and electron-accepting domains markedly enhances reduced-state persistence and productive electron transfer relative to the isolated components or their noncovalent combination. The resulting molecularly stored reducing equivalents enable room-temperature Birch-type reductions of polycyclic aromatic substrates in high yields using unprecedented catalytic receptor loadings. These results establish coupled cation binding and molecular electron storage as a supramolecular strategy for regulating highly reducing equivalents in solution-phase dearomatization chemistry.