A chemoselective polarity-mismatched photocatalytic C(sp3)–C(sp2) cross-coupling enabled by synergistic boron activation

Funding: J.B. thanks AstraZeneca and the Engineering and Physical Sciences Research Council (EPSRC) for a PhD studentship. A.J.B.W. thanks the Leverhulme Trust for a Research Fellowship (RF-2022-014) and the EPSRC Programme Grant “Boron: Beyond the Reagent” (EP/W007517) for support.We report the development of a C(sp3)–C(sp2) coupling reaction using styrene boronic acids and redox-active esters under photoredox catalysis. The reaction proceeds through an unusual polarity-mismatched radical addition mechanism that is orthogonal to established processes. Synergistic activation of the radical precursor and organoboron are critical mechanistic events. Activation of an N-hydroxyphthalimide (NHPI) ester by coordination to boron enables electron transfer, with decomposition leading to a nucleofuge rebound, activating the organoboron to radical addition. The unique mechanism enables chemoselective coupling of styrene boronic acids in the presence of other alkene radical acceptors. The scope and limitations of the reaction, and a detailed mechanistic investigation are presented.Publisher PDFPeer reviewe