A metal-free visible-light-promoted phosphorylation/cyclization reaction in water towards 3-phosphorylated benzothiophenes

A metal-free visible-light-induced 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN)-catalyzed phosphorylation/cyclization reaction was developed in water at room temperature for the synthesis of 3-phosphorylated benzothiophenes. Notably, the conventional organic solvents were avoided. More importantly, this silver-free system circumvents the generation of by-product benzo[b]phosphole oxides. With this strategy, a series of 3-phosphorylated benzothiophenes bearing various functional groups were synthesized in good to excellent yields.