Cu(I)-Photosensitizer Catalysis: A Tool for Conjunctive Olefination of Aldehydes.

The development of novel methodologies for olefin synthesis remains a central objective in synthetic chemistry, as olefins represent ubiquitous building blocks and versatile precursors for downstream transformations. The conventional Wittig reaction relies on phosphonium salts as carbon synthons, yet their synthesis requires alkyl halides that are often inaccessible for structurally complex substrates. Herein, we employ Cu(I)-photosensitizer catalysis to transform commercially available vinyl phosphonium salt into various elongated Wittig precursors under visible light irradiation, which subsequently react with aldehydes in a one-pot fashion to afford structurally diverse alkenes. This protocol synergistically combines the advantages of photoredox catalysis and the Wittig reaction, operates under mild conditions with excellent functional group tolerance, and accommodates readily available 1,4-dihydropyridines or silicates as modular radical sources, underscoring the practicality and flexibility of this approach.