Visible Light‐Promoted Fluorescein/Ni‐Catalyzed Synthesis of Bis‐(β‐Dicarbonyls) using Olefins as a Methylene Bridge Synthon

Herein, we report the synthesis of methylene‐bridged bis‐1,3‐dicarbonyls from olefins and 1,3‐dicarbonyls using a photoredox/nickel‐catalyzed synergistic approach. Styrene is reported as methylene one‐carbon (C1) synthons in the synthesis of bis‐(β‐dicarbonyls) for the first time. The deuterated study showed the incorporation of styrene‐d3 in the product by NMR and Mass analysis. Fluorescence quenching and cyclic voltammetry (CV) suggest that the reaction proceeds via an energy transfer process (EnT). The key aspects of the protocol are the use of benign photocatalyst fluorescein, peroxide‐free, air as oxidant, broader substrate scope, and 56% to 99% product yields. The synthetic application of the product has been extended to construct tetrasubstituted pyridines in a sequential one‐pot manner, bis‐isoxazole, and bis‐pyrazole. Synthesis of methylene‐bridged bis‐1,3‐dicarbonyls from olefins and 1,3‐dicarbonyls using a photoredox/nickel‐catalyzed synergistic approach has been reported. Notable features of the reaction are benign photocatalyst fluorescein, peroxide‐free, air as oxidant, broader substrate scope, and 56% to 99% product yields. The synthetic application of the product has been extended to construct tetrasubstituted pyridines, bis‐isoxazole, and bis‐pyrazole.