Visible-light-promoted bismuth-catalysed synthesis of dihydroquinoline scaffolds from β-enaminones

Dihydroquinolines are established as important scaffolds in medicinal chemistry owing to their ubiquitous occurrence in bioactive molecules. Utilising water as a solvent in photochemical synthesis provides a synthetic route for chemical transformations under mild conditions. Herein, we report a step-economical and efficient heterogeneous N-doped Bi₂WO₆ catalysis to obtain a diverse array of dihydroquinolines by using ammonium acetate as a cheap nitrogen source. The protocol exhibits excellent functional group tolerance and is amenable to gram-scale synthesis. The post-synthetic transformations open a window to access structurally complex as well as molecularly diverse heterocyclic scaffolds.