Organic Photoredox Catalytic Functionalization of Alkynones To Acess Heterocycles Containing 1,4-Dicarbonyl Structures and 3-Thioarylated Thioflavones

Herein, we report an efficient visible-light-mediated reaction of alkynones with ethyl diazoacetate for the construction of cyclic frameworks containing the 1,4-dicarbonyl moiety. In this photocatalytic system, a readily available phenothiazine derivative serves as the organic catalyst, which, upon photoexcitation, gains strong reducing power to facilitate the divergent synthesis of structurally diverse thioflavone derivatives. This metal-free protocol exhibits broad substrate scope and mild reaction conditions, providing a versatile and sustainable approach to high-value heterocycles.