One-pot and efficient protocol for preparation of some potent pharmaceutically valuable coumarin derivatives under solvent-free condition via direct coupling using biologically nontoxic organocatalyst, calix [4] arene tetrasulfonic acid (CSA), was introduced. Calix [4] arene sulfonic acid has been incorporated lately as a magnificent and recyclable organocatalyst for the synthesis of some organic compounds. Nontoxicity, solvent-free conditions, good-to-excellent yields for pharmaceutically significant structures, and ...
