Tertiary Phosphine Diversification via Photochemical P─C Chemoselective Cleavage of Phosphonium Salts

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Differentially substituted phosphines are indispensable in medicines, materials, and catalysis, yet their customizable synthesis, traditionally depending on unstable P─H/halogen reagents, remains formidably challenging. Here, we report a photoredox strategy enabling controllable aryl substitution through chemoselective P─C cleavage. By engineering electron donor‐acceptor complexes between phosphonium salts and tertiary amines, this metal‐free protocol realizes three consecutive hydrocarbyl exchanges for delivering tri‐diverse‐aryl phosphines with transition metal contamination elimination and broad functional group tolerance including unprotected amines and hydroxyls, facilitating late‐stage modification of drugs/commercial ligands and construction of P,O,S‐tridentate architectures and chiral P‐stereogenic centers. Mechanistic studies reveal the dynamic pentacoordinated‐phosphorane‐complex formation nature and the radical‐intermediate pathway, while the chemoselectivity originates from different P─C bond strengths. This work establishes a modular and sustainable platform for programming‐level precision phosphine engineering.