I2-Catalyzed three-component procedure for synthesis of substituted spiro[indoline-3,7′-pyrano[3,2-c:5,6-c′]dichromene]-2,6′,8′-trione derivatives

We report a facile and efficient method for synthesis of substituted spiro[indoline-3,7′-pyrano[5,6- c :5,6- c ′]dichromene]-2,6′,8′-trione derivatives by reaction of isatin and 4-hydroxy-2 H -chromen-2-one. As far as we are aware, few methods have been reported for preparation of these compounds. The reaction proceeded smoothly when promoted by molecular iodine. Because it is a non-toxic, low cost, and readily available reagent, iodine is a green catalyst for synthesis of these spiroheterocyclic compounds. The other advantages of the procure are high yields, simple operation, atom economy, and mild reaction conditions.