Sustainable photocatalytic synthesis of 2-hydroxybenzofuran-3(2H)-ones using lead-free Cs2AgBiBr6 nanocrystals†

The photocatalytic activation of oxygen molecules (O₂) is an environmentally friendly and sustainable alternative to substituted benzofuran-3(2H)-one synthesis. Herein, lead-free Cs₂AgBiBr₆ nanocrystals were used to activate O₂ efficiently and selectively for the photocatalytic transformation of 4-hydroxycoumarins to functional 2-hydroxy-benzofuran-3(2H)-ones under an air atmosphere. Polyfunctionalized benzofuran-3(2H)-ones with a quaternary carbon center can be selectively obtained in moderate to good yields at room temperature via one-pot synthesis. Perovskite crystal structures have significant influence on photocatalytic activity due to the different charge separation abilities. The reaction mechanism was further investigated to confirm the contribution of reactive oxygen species (ROS).