A different route to 3-aryl-4-hydroxycoumarins

We herein report the simple and direct arylation of 4-hydroxycoumarins by photoinduced reaction with aryl halides (iodobenzene, iodonaphthalene, 4-iodoanisole, 2-iodoanisole). Good yields of 3,4-disubstituted coumarins were obtained in these reactions (>60%). Extension of the procedure to the reaction with o-dihalobenzenes leads to the synthesis of ring closure products which bear a tetracyclic aromatic-condensed ring system, although in lower overall yields (≈45%).