Phthalimide-N-sulfonic acid as a recyclable organocatalyst for an efficient and eco-friendly synthesis of 2-(2-oxo-2H-chromen-3-yl)-4-aryl-indeno[1,2-b]pyridine-5-one derivatives

A facile and environmentally benign synthesis of some 2-(2-oxo-2H-chromen-3-yl)-4-aryl-indeno[1,2-b]pyridine-5-one derivatives from the reaction of aromatic aldehydes, 3-acetylcoumarin, 1,3-indandione and ammonium acetate using phthalimide-N-sulfonic acid (PISA) as a catalyst is described. The present method has some important features such as mild reaction conditions, short reaction times, less catalyst dosage and high yields with the green aspects by avoiding toxic catalysts and solvents. Further, the catalyst can be reused for four times without any noticeable decrease in the catalytic activity