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

We reported a pentacoordinated-phosphorane EDA complex system to achieve chemoselective P─C cleavage. Through iterative implementation, this protocol realized consecutive aryl substitutions, yielding tri-diverse-aryl phosphines with customizable architectures. The metal-free and one-pot strategy demonstrated wide applications in gram-scale synthesis, post-modification of commercial ligands, and construction of P-stereogenic centers.

Abstract

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.

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