Consecutive mechanical-force-induced electron transfer for reduction of aryl halides with high reduction potentials

Mechanical-force-induced redox catalysis has emerged as a green and expeditous approach in synthetic chemistry, relying on single-electron transfer from polarized piezoelectric materials to substrates initiated by mechanical agitation. However, the piezoelectric potential generated can sometimes be insufficient to activate the electron transfer process, similar to the limitations observed in photocatalytic reactions. In this work, we introduce a catalytic strategy employing a consecutive mechanical-force-induced electron transfer (ConMET) strategy. This strategy uses piezoelectric materials as mechanochemical redox catalysts with 9-phenyl-dihydroacridine as a sacrificial electron donor, enabling efficient consecutive electron transfer. Our method effectively reduces aryl iodides, bromides, and even electron-rich aryl chlorides, which possess reduction potentials as high as -2.8 V (vs. SCE), leading to the formation of aryl radicals. Ultimately, this strategy facilitates anti-Markovnikov hydroarylation of alkenes and dehalogenative deuteration of aromatic halides under mild conditions.